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WO2024170703A1 - Optometry system for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens - Google Patents

Optometry system for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens Download PDF

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Publication number
WO2024170703A1
WO2024170703A1 PCT/EP2024/053908 EP2024053908W WO2024170703A1 WO 2024170703 A1 WO2024170703 A1 WO 2024170703A1 EP 2024053908 W EP2024053908 W EP 2024053908W WO 2024170703 A1 WO2024170703 A1 WO 2024170703A1
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WO
WIPO (PCT)
Prior art keywords
value
mesopic
individual
vision correction
eyes
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Ceased
Application number
PCT/EP2024/053908
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French (fr)
Inventor
Nacer LAKHCHAF
Susana MONTECELO SALVADO
Andrès GENE SAMPEDRO
Mercedes BASULTO MARSE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EssilorLuxottica SA
Original Assignee
Essilor International Compagnie Generale dOptique SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Essilor International Compagnie Generale dOptique SA filed Critical Essilor International Compagnie Generale dOptique SA
Priority to CN202480012613.9A priority Critical patent/CN120751974A/en
Priority to EP24705156.8A priority patent/EP4665202A1/en
Publication of WO2024170703A1 publication Critical patent/WO2024170703A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/02—Subjective types, i.e. testing apparatus requiring the active assistance of the patient
    • A61B3/028—Subjective types, i.e. testing apparatus requiring the active assistance of the patient for testing visual acuity; for determination of refraction, e.g. phoropters

Definitions

  • TITLE OPTOMETRY SYSTEM FOR DETERMINING, FOR EACH EYE OF AN INDIVIDUAL, A MESOPIC VALUE OF A VISION CORRECTION POWER OF A CORRECTIVE LENS
  • the invention relates to an optometry system for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens.
  • an individual may be tested during a subjective test protocol, using a phoropter allowing placing successively in front of his eye lenses to provide different test values of said vision correction power to each of the eyes of the individual.
  • This test protocol may be achieved using a classical phoropter or a phoropter having lenses of continuous variable power.
  • the individual is asked to express a visual assessment that corresponds to an indication of a preferred visual state among two visual states presented to him or if he cannot decide between the two.
  • the two visual states may correspond to his vision of two different images through the current lens power or may correspond to his vision through the previous lens power and his vision through the current lens power, for example.
  • Photopic light conditions correspond to the conditions experienced in daylight or with other bright light, where vision is believed to involve mainly the cones of the retina. They may be defined as a range of high light levels above rod saturation where vision is mediated by signals from cone photoreceptors. Photopic light conditions implying photopic vision of the eye correspond to a luminance strictly over 5 cd/m 2 at eye level according to CIE 191 :2010 “Recommended system for mesopic photometry based on visual performance technical report”.
  • Scotopic light conditions correspond to the conditions experienced at night, with very low level of luminance. Scotopic vision is produced exclusively through rod cells, which are most sensitive to wavelengths of around 498 nm (bluegreen) and are insensitive to wavelengths longer than about 640 nm (red-orange). Scotopic light conditions are typically below 0.005 cd/m 2 in luminance at eye level according to the last CIE 191 :2010 “Recommended system for mesopic photometry based on visual performance technical report”.
  • Mesopic light conditions correspond to the conditions experienced between twilight with low level of luminance and night. They may be defined as a range of intermediate light levels between cone threshold and rod saturation where both rod and cone signals contribute to a visual response. Mesopic vision is therefore a combination of photopic and scotopic vision with cones and rods involved. Moreover, the respective contribution of cones and rods can vary within the mesopic range. Mesopic light conditions range approximately from 0.005 to 5.0 cd/m 2 in luminance at eye level.
  • the vision correction powers determined during above mentioned photopic subjective tests are therefore adapted to correct the visual defects of the eyes of the individual in photopic light conditions.
  • This refraction shift may not be assessed through most currently used protocols of subjective refraction tests.
  • one object of the invention is to provide a new optometry system adapted to perform a subjective refraction in mesopic conditions.
  • an optometry system for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions, said system comprising an optometry device having a refraction test unit with two optical refraction elements, each optical refraction element being adapted to provide test values of said vision correction power to one of the eyes of the individual, said optometry system comprising a computer with one or more processors programmed to: a) control the optometry device to determine a photopic value of said vision correction power of said corrective lens for each eye of said individual by achieving a photopic subjective refraction test in light conditions ensuring photopic vision of the eyes of the individual or to retrieve an initial vision correction value stored in a memory of the optometry system, or to collect an initial vision correction value, b) validate a step of placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time
  • the optometry system of the invention it is possible to determine said mesopic correction power in a quick and reliable manner.
  • step e said one or more processors are programmed to perform, in step e), a final mesopic visual appreciation test with the following steps:
  • determining said mesopic value of vision correction power for each eye of the individual by adding a refining value of spherical power to said mesopic raw value of the vision correction power for each eye, aiming at improving the quality of mesopic vision and depending on said predetermined negative value of spherical power ;
  • the refining value of spherical power added by said one or more processors comprises one of the following :
  • said one or more processors are programmed to add the refining value of spherical power equal to said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power ;
  • said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and when said answer indicates a slight or moderate difference in the visual performance of the eyes of the individual in favor of his visual performance with the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power ;
  • said one or more processors are programmed to determine said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power as being equal to a fraction of the predetermined negative value of spherical power ;
  • said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and when said answer indicates an important difference in the visual performance of the eyes of the individual in favor of his visual performance with the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said predetermined negative value of spherical power ;
  • said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and when said answer indicates a slight or moderate difference in the visual performance of the eyes of the individual in favor of his visual performance without the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said null value ;
  • said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and when said answer indicates an important difference in the visual performance of the eyes of the individual in favor of his visual performance without the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power ;
  • said one or more processors are programmed to determine said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power as being equal to a fraction of the absolute value of said predetermined negative value of spherical power ;
  • said one or more processors are programmed to determine, in step d) or e), a binocular visual acuity of the eyes, each eye being provided with the corresponding photopic value of the vision correction power determined in step a) ;
  • said one or more processors are programmed to perform a step of evaluation of the visual performances of the subject while his eyes are placed in light conditions ensuring mesopic vision and provided either with the photopic value of the vision correction power determined in step a) or with the mesopic value of the vision correction power determined in step e) ;
  • an autorefractometer configured to determine, for each eye of said individual, a determined initial vision correction power value, and/or a memory storing for each eye a stored initial vision correction power value and/or an entry unit collecting for each eye a collected initial vision correction power value, and wherein, said one or more processors are programmed to perform a preliminary step to set an initial photopic value of said vision correction power in light conditions ensuring photopic vision of the eye of the individual, as being equal to said determined and/or stored and/or collected initial vision correction power value for each of the eyes of the individual ;
  • said one or more processors are programmed to validate said step of placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual with said predetermined amount of time being comprised between 2 minutes and 10 minutes, more preferably between 2 minutes and 5 minutes, more preferably equals to 2.5 minutes;
  • the optometry system comprises an input device for collecting the answers of the individual and wherein said one or more processors are programmed to set each next test value provided by said optical refraction element according to the last answer collected by said input device from the individual ;
  • the optometry system comprises a screen adapted to display vision tests and wherein said one or more processors are programmed to control the luminance of the screen depending on the light conditions ensuring photopic, scotopic or mesopic vision in which the eyes of the individual are placed ;
  • - it comprises a main casing enclosing the screen and to which the optometry device is mounted so as to allow the individual to see the screen through the optical refraction elements of the optometry device, and including an internal optical system allowing the observation of an image of the screen at several observation distances.
  • the invention also relates to a method for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic vision conditions, using an optometry device having a refraction test unit with two optical refraction elements, each optical refraction element being adapted to provide test values of said vision correction power to one of the eyes of the individual, said method comprising the following steps: a) determining a photopic value of said vision correction power of said corrective lens for each eye of said individual by achieving a photopic subjective refraction test in light conditions ensuring photopic vision of the eyes of the individual or to retrieve an initial vision correction value stored in a memory of the optometry system, or to collect an initial vision correction value, b) placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time, c) placing the eyes of the individual in light conditions ensuring mesopic vision of the eyes of the individual and d)
  • the invention also relates to an optical article designed such as to provide a vision correction equal to the mesopic value of vision correction power determined with the optometry system and method according to the invention.
  • Said optical article can possibly also include a filter and/or an anti reflective coating known to be suited to improve an individual’s vision in mesopic lighting conditions and/or reduce glare.
  • the invention furthermore relates to a set of optical articles including a first optical article designed based on the mesopic value of vision correction power determined according to the invention, and a second optical article designed such as to provide a vision correction equal to the photopic vision correction.
  • such a set of optical articles can include for example a first optical article such as an ophthalmic lens designed with the mesopic vision correction, and a second optical article such as an ophthalmic lens designed with the photopic vision correction.
  • the first optical article can consist in a mesopic clip comprising ophthalmic lenses adapted to be removably associated with the second optical article.
  • Each ophthalmic lens of said mesopic clip is designed to provide, in association with a corresponding lens of the second photopic optical article, a global vision correction that is equal to the mesopic vision correction.
  • the ophthalmic lens of the mesopic clip associated with each eye of the individual is designed with a sphere calculated or equal to the corresponding mesopic refraction shift determined thanks to the system and method according to the invention, the mesopic refraction shift being equal to a difference between a (raw or refined) mesopic vision correction and a photopic vision correction.
  • FIG. 2 is a block diagram of steps of a subjective refraction test in photopic conditions implemented in an embodiment of step a) of the method according to the invention
  • FIG. 3 is a block diagram of steps of a subjective refraction test in mesopic light conditions implemented in an embodiment of step d) of the method according to the invention
  • FIG. 4 is a block diagram of steps of a visual appreciation test in mesopic light conditions implemented in an embodiment of step e) of the method according to the invention
  • FIG. 5 is an example of a test image comprising a line of Sloan letters of typical EDTRS chart with an achromatic grey background of mesopic luminance
  • FIG. 6 is a graph showing the refraction shift determined for two different test background luminance, the refraction shift being in this graph, equal to a difference between a refined mesopic vision correction and a photopic vision correction, the dark adaptation time being 5 minutes and the number of test subjects being 36,
  • FIG. 7 is a Bland-Atman plot showing the difference between the refined mesopic refraction shifts determined through mesopic refraction tests using test images having a background luminance of 0.36 and 1.1 cd/m 2 as a function of the mean mesopic refraction shift determined for the corresponding tests, the dark adaptation time being 5 minutes and the number of test subjects being 36,
  • FIG. 8 is a graph showing visual acuity shifts determined in mesopic light conditions while using test images having a background luminance of 0.36 or 1.1 cd/m 2 and providing the individual with lenses exhibiting a vision correction power equal to a photopic value of vision correction power (referenced as “w/photopic Rx” on figure 8) or to a mesopic value of vision correction power (referenced as “w/mesopic Rx” on figure 8),
  • FIG. 9 shows schematically visual acuity variations of an individual tested in different light conditions and with a photopic refraction test (referenced as “regular refraction” or “photopic Rx” on figure 9) or to a mesopic refraction test (referenced as “mesopic Rx” on figure 9),
  • FIG. 10 is a graph showing (left: “w/photopic Rx”) visual acuity shifts observed when light conditions go from photopic to mesopic light conditions while the individual wears the photopic vision correction and (right: “w/mesopic Rx”) visual acuity shifts observed when the individual wears from the photopic vision correction to the mesopic vision correction, while light conditions remains mesopic light conditions, the number of test subjects being 96, all presenting a Rx shift,
  • FIG. 11 is a graph showing refraction shifts values measured between two successive mesopic refraction tests according to the invention comprising each a photopic light conditions step, a dark adaptation step, and a mesopic light conditions step, the two successive mesopic refraction tests being separated by a re-adaptation period to photopic light conditions in order to ensure retinal adaptation state before the second mesopic refraction test, and having two different times of (left) 5 minutes and (right) 2.5 minutes of dark adaptation step ,the dark adaptation time of the first mesopic refraction test being randomly set to 5 minutes or 2.5 minutes so as to avoid in the results obtained, an effect of the order in which the lowest dark adaptation time is used in the first or the second mesopic refraction test, the number of test subjects being 82,
  • FIG. 12 is a Bland-Atman’s plot showing the difference between the refraction shifts determined with tests involving different dark adaptation times (2.5 and 5 minutes) as a function of the mean refraction shift determined for the corresponding tests, the dark adaptation times of the mesopic refraction tests being randomly set as for the figure 11 and for the same reasons, and the number of test subjects being 82,
  • FIG. 13 is a graph showing visual acuity shifts determined in mesopic light conditions, the individual being provided with lenses exhibiting a vision correction power equal to a mesopic value of vision correction power (NIGHT Rx) when using a dark adaptation time of 2.5 or 5 minutes, the dark adaptation times being randomly set as for the figure 11 and for the same reasons,, the number of test subjects being 82, all presenting a Rx shift with both dark adaptation times,
  • - Figure 14 is a Bland-Altman's plot showing the difference between the refined mesopic refraction shifts determined at two different times V1 and V2 for testing reproducibility of the method according to the invention, difference between visit 1 and visit 2 (V1 & V2) being on average 60 days; the number of test subjects being 54, all non-presbyopes, 1.1 cd/m2 test luminance and 5-min dark adaptation time, showing agreement in refined Rx shift between visit 1 & 2, - Figure 15 shows a distribution and mean values of refined Rx shift in diopters (D) measured under 5-min dark adaptation time and 1.1 cd/m2 test luminance conditions; the number of test subjects being 115 (82 non-presbyopes and 33 presbyopes)
  • the invention principally relates to an optometry system for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions according to a method of the invention.
  • the optometry system allows determining said mesopic value of the vision correction power of the corrective lens with the purpose of manufacturing this corrective lens to be mounted in a vision correction equipment used by said individual.
  • Said optometry system is configured to implement a subjective refraction determination at several observation distances, including and preferably far distance, but also possibly intermediate and near distance.
  • Such optometry system comprises a screen to display an eye chart to be observed by the individual, a phoropter (also called “refractometer”) designed for providing one test lens or multiple test lenses with different vision correction powers close to the eye of the individual, through which the individual observes an eye chart, the vision correction powers of the phoropter being changed according to the answers provided by the individual relative to its ability to see optotypes, for example characters, of the eye chart through the test lens providing a vision correction power.
  • a phoropter also called “refractometer”
  • the screen is placed at 5-6 meters from the phoropter to simulate an observation distance at the infinity, and the eye chart is displayed in a conventional examination room with controlled lighting conditions.
  • the characters of the eye chart and the background of the characters have their own luminance.
  • the individual observes the image displayed by the screen through the vision correction powers at an observation distance equal to the distance between the screen and the phoropter of 5-6 meters, which could be approximated to the infinity.
  • the screen For smaller examination rooms, when the screen cannot be placed at 5-6 meters to approximate infinity, or for “compact optometry system” specifically designed to reproduce, in a compact version, an examination room, the screen is placed closer to the phoropter and an optical system allows defining a larger distance of observation than the physical distance separating the screen from the phoropter.
  • the phoropter belongs to an optometry device having a casing or housing simulating an examination room.
  • the casing or housing encloses a display unit suitable for displaying a test picture to be seen through the phoropter 100, placed at a short distance from the phoropter, but observed by the individual at several observation distances, thanks to an internal optical system.
  • Figure 1 shows a schematic view of an example of such an optometry system 10 for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions according to the invention.
  • Said optometry system 10 comprises an optometry device 20 having a refraction test unit 30 with two optical refraction elements 31 , each optical refraction element being adapted to provide different test values of said vision correction power to one of the eyes of the individual.
  • the optometry system 10 also comprises a display unit 40 adapted to produce a visual test image for the individual’s eye, said visual test image being visible through an exit aperture of said refraction test unit 30 of the optometry device 20.
  • the refraction test unit 30 is interposed between the display unit 40 and the individual’s eye. It is movable so that its position may be adjusted in front of the eyes of the individual.
  • Said refraction test unit 30 may be of any kind known to the man skilled in the art. Such refraction test unit 30 is usually called “phoropter”. It is adapted to provide a variable optical correction for the individual’s eye looking therethrough.
  • the optical refraction elements comprise for example a lens with variable power and an optical component with a continuously variable cylindrical power and axis. It comprises here a deformable liquid lens having an adjustable shape.
  • the optical refraction element may comprise an ensemble of non-deformable lenses having different optical powers, and a mechanical system that enables to select some of these lenses to group them to form the set of lenses through which the individual can look.
  • the refractive power of the set of lenses one or several lenses of the set of lenses are replaced by other lenses stored in the refraction test unit.
  • the refraction test unit may also include a pair of independently rotatable lenses each having a cylindrical power.
  • the lens with variable power or the different test lenses are configured to provide the test values of said vision correction power.
  • the refraction test unit 30 optionally comprises one or more elements designed to receive the head of the individual and hold it in a predetermined position relative to the refraction test unit 30.
  • This element may for example receive the forehead of the individual.
  • the refraction test unit could comprise an element to receive the chin of the individual.
  • Such refraction test unit 30 is well-known and will not be described in more details here.
  • the light beam exiting the display unit 40 is directed through the lens or lenses of the refraction test unit 30 towards the eye of the individual.
  • the display unit 40 is adapted to produce both a visual test image and a scene image for the individual’s eye.
  • the visual test image is a virtual image formed by a projection optical system (and more precisely by a first projection sub-system which projects a visual test picture displayed on a visual test screen 41 (first screen) and by an optical element (if present as explained later), that optically transforms said visual test picture into the virtual visual test image.
  • the display unit 40 comprises:
  • an internal optical system 42 allowing the observation of an image of the screen at several observation distances.
  • Said internal optical system 42 produces the visual test image observed by the individual through the refraction test unit 30 based at a variable distance from said exit aperture.
  • the optometry system may provide a visual test image at a fixed distance.
  • the optometry system is configured to provide said visual test image at least at an observation distance of far vision from the eyes of the individual, for example at an observation distance equal or higher than 5 meters, preferentially 6 meters from the eyes of the individual.
  • Said vision tests typically comprise a test picture.
  • the image of said test picture through said internal optical system 42 produces said visual test image.
  • the distance between said visual test image and said exit aperture, and thus the observation distance between the visual test image and the eye of the individual may be varied, for example between an observation distance of far vision and a different observation distance of near or intermediate vision.
  • An observation distance of far vision is generally considered to be above 5 to 6 meters, up to infinity.
  • An observation distance of intermediate vision is generally considered as being comprised between 40 centimeters and 5 meters.
  • An observation distance of near vision is generally conserved as being comprised between 40 and 33 centimeters.
  • the optometry device 20 includes a casing 2 adapted to be placed on a table, for instance, or to be mounted on a stand to be placed on a table or on the floor.
  • the casing 2 encloses here the display unit 40 comprising the screen 41 and the internal optical system 42.
  • the refraction test unit 30 is mounted on the casing 2.
  • the first screen 41 is for instance one of the following: a LED or OLED screen, a serigraphy with backlight screen, a display light projection screen with micro video projector, an LCD screen or a TFT screen. It produces a light beam along a screen axis S perpendicular to the mean plane of the screen 41 . This light beam is meant to produce an image of an object, such as an optotype, for an individual using the optometry device.
  • the test picture or image displayed by the screen 41 comprises a background and a visual target such as an optotype, for example Sloan letters or another type of letters, numbers, Landolt’s C or Snellen’s E or drawings.
  • a test image may comprise an acuity chart, such as a ETDRS chart, including optotypes of a specific optotype luminance, such as Sloan letters, and a background such as an achromatic uniform color of a specific background luminance (white or grey).
  • Other types of pictures adapted to test the vision of the individual may be used, as known by the man skilled in the art.
  • the test picture may also comprise a duochrome test.
  • the scene image is a virtual image formed by a projection optical system (and more precisely by the second projection sub-system) which projects a background picture displayed on a scene screen (or second screen), that optically transforms said scene picture into the virtual scene image.
  • This background picture is preferably of an environment familiar to the individual, for example a natural environment, exterior or interior, such as a city, a landscape, a road or a room, and more preferably for mesopic conditions, a road at night seen through the windshield of an automobile (for example a part of a dashboard, steering wheel and of the rearview mirror of the automobile) surrounded by a landscape (trees, hills, clouds, city environment etc).
  • the second screen is for instance one of the following: a LED or OLED screen, a serigraphy with backlight screen, a display light projection screen with micro video projector, an LCD screen or a TFT screen. It produces a light beam along a screen axis S perpendicular to the mean plane of the second screen. This light beam is meant to produce an image of a background picture (landscape, road, town... ).
  • the first and second projection sub-system allows the scene image to be superimposed with the visual test image and to be visible by the individual through the vision correction optical system, the scene image being observed at a background distance of projection from the individual’s eye 1 , whereas the test image being observed at the variable distance set.
  • this background distance of projection is greater than or equal to the visual test distance of projection.
  • Such optometry system 10 is for example illustrated in documents EP3711654, EP3298952, EP3298951 , or EP4231892 and will not be described here in more details.
  • the visual target is displayed on said background.
  • the luminance of the visual target, the luminance of the background of the screen, and the luminance of the casing may be controlled independently from one another and/or depending on specific light conditions to be used while performing the mesopic subjective refraction test.
  • the illustrated optometry system 10 and the optometry system involving a screen and a phoropter separated by a large distance (4-6 meters) in an examination room comprise, according to the invention, an input device 60 for collecting information and answers of the individual, a computer to control the vision correction powers to apply to each eye, and the eyechart and background luminances depending on the progress of the subjective mesopic refraction determination method, as defined below.
  • the input device 60 may comprise a joystick, a mouse, a keypad, or other input devices.
  • Said optometry system 10 also comprises a computer 50 with one or more processors programmed to: a) control the optometry device to determine a photopic value of said vision correction power of said corrective lens for each eye of said individual by achieving a photopic subjective refraction test in light conditions ensuring photopic vision of the eyes of the individual, or to retrieve an initial vision correction value stored in a memory of the optometry system, or to collect an initial vision correction value, b) validate a step of placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time, c) validate a step of placing the eyes of the individual in mesopic light conditions ensuring mesopic vision of the eyes of the individual and d) control the optometry device to achieve a mesopic subjective refraction test, said mesopic subjective refraction test comprising:
  • Said one or more processors are programmed to control the luminance of the screen 41 depending on the light conditions ensuring photopic, scotopic and mesopic vision in which the eyes of the individual are placed.
  • Said vision correction power may comprise a sphere value, and/or a cylinder value of an ophthalmic lens designed to correct the vision of the individual.
  • step a) the optometry device 20 is controlled by the computer 50 to determine a photopic value of said vision correction power of said corrective lens for each eye of said individual.
  • a photopic subjective refraction test is achieved in light conditions ensuring photopic vision of the eyes of the individual.
  • This photopic subjective refraction test corresponds to a conventional subjective refraction test and any known protocol for performing said subjective test may be used.
  • a maximum-plus maximum-visual acuity power (MPMVA power) is determined through the conventional photopic subjective test achieved.
  • MPMVA power maximum-plus maximum-visual acuity power corresponds to the most convex sphere value of the test values of the vision correction power provided to the eye of the individual allowing the best visual acuity of this eye.
  • Step a) aims to ensure the best focus under relaxed accommodation conditions of the eye before performing a subjective test in mesopic light conditions.
  • Step a) is performed under usual photopic light conditions.
  • the usual photopic light conditions are obtained in a room with lights on, providing an illuminance at the individual’s eyes level between 10 and 350 lux, more preferably of about 45 ⁇ 5 lux.
  • Said one or more processors are programmed to control the luminance of the background of said optotypes to provide photopic light conditions. They may also control the light of the room where step a) is achieved.
  • the screen 41 of the display unit 40 is used to display a test picture comprising a visual target with a background luminance surrounding the visual target being comprised between 80 and 320 cd/m2, ideally around 200 cd/m 2 and preferably of about 180 candela per meter square (cd/m 2 ).
  • the test picture is displayed with high contrast and high-luminance features.
  • said optometry system comprises a device for determining an objective value of the vision correction power needed by each eye of the individual by aberrometry, automated refraction or retinoscopy.
  • the optometry system comprises for example an autorefractometer configured to determine, for each eye of said individual, a determined initial vision correction power value in photopic light conditions.
  • said optometry system comprises a memory storing for each eye a stored initial vision correction power value in photopic light conditions.
  • step a) said input device 60 is used to collect, for each eye of the individual, a collected initial vision correction power value.
  • said one or more processors are programmed to perform a preliminary step to set an initial photopic value of said vision correction power in photopic light conditions, as being equal to said determined and/or stored and/or collected initial vision correction power value for each of the eyes of the individual.
  • Said one or more processors are then programmed to start implementing said photopic subjective refraction test on the basis of said initial photopic value of said vision correction power for each eye of the individual.
  • the conventional photopic subjective test includes for example the following steps: i) monocular fogging of a first eye, ii) monocular defogging of said first eye, iii) monocular sphere searching aiming to determine the most convex sphere value of the test values provided to the eye of the individual allowing the best monocular visual acuity of this eye (monocular MPMVA), iv) monocular cylinder searching for said first eye, v) iteration of the previous step for the second eye, vi) bi-ocular balance or bi-ocular sphere adjustment determined for each eye while keeping both of the eyes of the individual open, vii) binocular balance or binocular sphere adjustment aiming to determine the most convex sphere value of the test values provided to both eyes of the individual allowing the best binocular visual acuity (binocular MPMVA); viii) measurement of photopic monocular and binocular visual acuity.
  • the expression “bi-ocular” in “bi-ocular balance” will be used to indicate that the visual test performed allows testing one eye separately from the other, while keeping both eyes opened, thanks for example, to polarized lenses or prismatic lenses.
  • the expression binocular balance will be used to indicate that the visual test performed allows testing both eyes at the same time, while keeping both eyes opened. This is achieved by providing the same test image to the eyes.
  • the photopic subjective test is classically performed by presenting said visual test images to the individual and asking him to assess the quality of his perception of the visual targets of said visual test images and/or to identify optotypes characters.
  • the individual is usually asked to compare his perception of two different visual test images or to identify characters of two different visual test images.
  • the answers of the individual are provided to said computer 50 thanks to said input device 60.
  • Said one or more processors are programmed to set each next test value provided by said optical refraction element of the refraction test unit 30 according to the last answer collected by said input device 60 from the individual.
  • the step vii) of binocular balance may be performed from bi-ocular values determined in the step vi).
  • the binocular balance step is generally handled as follows:
  • a same binocular visual test image is provided to both eyes (block 100 of figure 2), then, a same positive predetermined spherical power value is added to said bi-ocular values determined in the step vi), to slightly fog both eyes, then a negative predetermined value of spherical power is iteratively added, until a maximum value of the photopic binocular visual acuity is reached.
  • a same positive spherical power for example equal to +0.25 diopters (D) is initially added to the current bi-ocular test value of each eye determined in step vi) (block 101 ) to slightly fog both eyes.
  • the one or more processors are then programmed to perform a visual acuity test (block 102).
  • the visual acuity is identified as having decreased (arrow 104)
  • said same positive spherical power is sufficient to slightly fog the individual’s vision and the binocular balance step can continue.
  • the one or more processors are programmed to iteratively add additional predetermined fogging spherical power values until the visual acuity is identified as having decreased (arrow 104), the cumulative fogging spherical power values being at this stage sufficient to slightly fog the individual’s vision.
  • the identification of a visual acuity decrease by the one or more processors can occur when the visual acuity is decreased by a minimal predetermined value, for example when an interface between an operator and the one or more processors is controlled by the operator to indicate such a decrease, for example when the operator observes that the individual cannot identify at least 3 characters out of 5 in a same line of an EDTRS visual chart.
  • the one or more processors are programmed to iteratively add a negative predetermined value of spherical power, until a maximum value of the photopic binocular visual acuity is reached.
  • a first negative predetermined value of spherical power is added (block 105) corresponding in absolute value to the last added fogging spherical power value. For example, if the last added additional predetermined value of fogging spherical power equals +0.25 diopters (D), this value is removed from the current test value of each eye (block 105).
  • the one or more processors are then programmed to perform a visual acuity test (block 106).
  • said one or more processors are programmed to iteratively continue to add a negative predetermined value of spherical power to the current test value and to determine, each time said negative predetermined value of spherical power is added, a photopic binocular visual acuity of the eyes, until a maximum value of the binocular visual acuity is reached.
  • the visual acuity is identified as not having improved (arrow 108), a maximum value of the binocular visual acuity has been reached.
  • the identification of the maximum value of the binocular visual acuity occurs when, further to the addition of a negative predetermined value of spherical power, the visual acuity that was previously recording as improving decreases or does not improve with the last added value of the negative predetermined value of spherical power.
  • the last added value of the negative predetermined value of spherical power is removed (block 109) and the obtained test value is considered as the photopic binocular visual acuity of the eyes for which a maximum value of the binocular visual acuity is reached.
  • visual acuity improvement can be characterized by the identification by the individual of 3 out of 5 characters of a line in a ETDRS chart
  • the one or more processors are programmed to undo the addition of the last increment of negative spherical power. For example, a positive sphere power equal to the opposite of the last negative increment of sphere power is added, for example +0.25 diopters (D) is added to the current test value of each eye (block 109).
  • the final current test value then corresponds to the most convex sphere values allowing the best visual acuity in photopic light conditions.
  • the photopic subjective refraction test is ended (block 110).
  • the photopic subjective refraction test provides, for each eye of the individual, the most convex sphere values allowing the best visual acuity in photopic light conditions corresponding to the binocular photopic MPMVA power (Maximum Plus Maximum Visual Acuity power). These values are used preferably to determine monocular and binocular visual acuities, and to start the mesopic subjective refraction test, as described hereafter.
  • the one or more processors of the computer 50 are programmed to request the achievement of a step of placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time.
  • the individual or the user of the optometry system 10 is then required to perform an action indicating that this step has been achieved through the input device 60 of the system.
  • This action may comprise checking or clicking a validate button.
  • said one or more processors requests that the individual is subjected to a short-time adaptation to the dark.
  • the individual is placed in scotopic vision conditions providing a luminance at the individual’s eyes level of less than 0.005 cd/m 2
  • Said predetermined amount of time is comprised between 2 minutes and 10 minutes, more preferably between 2 minutes and 5 minutes, more preferably equals to 2.5 minutes. It is preferentially over 2 minutes, preferentially equal to 2.5 minutes or more.
  • Adapting the eyes of the individual to scotopic vision light conditions avoids mesopic visual acuity fluctuation due to progressive changes in the eyes sensitivity after passing directly from photopic to mesopic light conditions.
  • the optometry system 10 may comprise additional accessories to obtain said scotopic vision light conditions, such as occluders or dark cover for the optometry device, sunglasses or opaque mask for the eyes of the individual.
  • the step of placing the individual in said scotopic vision light conditions may in particular be performed by:
  • immersive mask as for instance a virtual reality face mask
  • Said one or more processors may be programmed to control the lights of the room and/or the lights of the optometry device when step b) is carried out.
  • the one or more processors of the computer 50 can be programmed to broadcast pre-registered audio information on the next steps of the test, pre-registered questions to the subject relative to his/her discomfort/difficulties encountered specifically at night, for example when driving, and/or collect oral and/or visual input responses/reactions/behaviours of the subject during the step of placing the individual in said scotopic vision light conditions.
  • step b) aiming to adapt the eyes of the individual to darkness, said one or more processors of the computer 50 are programmed to request the achievement of a step of placing the eyes of the individual in light conditions ensuring mesopic vision of the eye of the individual.
  • the individual or the user of the optometry system 10 is then required to perform an action indicating that this step has been achieved through the input device 60 of the system.
  • This action may comprise checking or clicking a validate button.
  • the individual is placed in mesopic light conditions providing a luminance at the individual’s eyes level between 0.005 and 5 cd/m 2 more preferably about 1 cd/m2. This is obtained in a dark room with a minimum of artificial or natural light allowing said mesopic light conditions, and preferably with no artificial or natural light.
  • Other parasite light sources should also preferably be avoided.
  • Said one or more processors may be programmed to control the lights of the room where step c) is carried out.
  • Said one or more processors are programmed to control the optometry device 20 to achieve a mesopic subjective refraction test.
  • the light conditions of the room are mesopic light conditions, provided preferably with a dark room or with a minimum of artificial or natural light.
  • Said one or more processors are programmed to control the luminance of the background of said acuity chart to provide mesopic light conditions and the luminance of the optotypes of the acuity chart themselves to provide scotopic or mesopic conditions.
  • the screen 41 of the optometry system 20 is controlled by said one or more processors to display visual acuity optotypes such as Sloan letters, numbers, Snellen’s E or Landolt’s C or drawings with mesopic luminance between 0.005 and 5 cd/m 2 (for example 0.04 cd/m 2 ) or with scotopic luminance below 0.005 cd/m 2 , and the background of said optotypes with mesopic luminance comprised between 0.005 and 5 cd/m 2 , for example equal to about 1 cd/m 2 .
  • An adjustment of the binocular sphere only is conducted by searching the MPMVA power according to the steps described hereafter.
  • Said one or more processors are programmed to control the luminance of the screen depending on the light conditions ensuring photopic, scotopic and mesopic vision in which the eyes of the individual are placed.
  • the luminance level of the room of a non-compact optometry system and/or of the casing of a compact optometry system may differ from the luminance level of the screen (visual tests) for a same light environment condition (photopic, mesopic, scotopic).
  • luminances of the chart background, of the room and/or of the casing of the non-compact optometry system should all be in the mesopic levels, and the luminance level of the chart background should preferably be higher than the luminance level of the room and/or of the casing of the compact optometry system, for example higher by at least as 5 percent.
  • the eyes of the individual are provided with the photopic values of the vision correction power determined in step a).
  • the one or more processors are programmed to determine the binocular visual acuity of the eyes with each eye provided with said photopic value of the vision correction power determined in step a), while the eyes are placed in mesopic light conditions (block 200 of figure 3). This step may also be performed during step e) instead, as mentioned below.
  • This first sub-step provides information on the shift in visual acuity induced by the change in lighting environment.
  • the visual acuity value obtained in this first sub-step it is possible to compare the visual acuity obtained with the photopic value of the vision correction power determined in step a) in photopic light conditions and the visual acuity obtained with the photopic value of the vision correction power in mesopic light conditions of the current first sub-step.
  • the one or more processors are programmed to provide to each eye a fogging test value of vision correction power equal to a predetermined fogging spherical power added to the corresponding photopic value of the vision correction power, in order to fog both eyes, the individual still being exposed to mesopic light conditions.
  • a positive sphere power for example equal to +0.5 diopters (D) is added to the current test value of each eye (block 201 ).
  • the one or more processors are then optionally programmed to perform a visual acuity test which should confirm that further to the addition of the same positive spherical power, the visual acuity is identified as having decreased.
  • the one or more processors are programmed to add to both eyes at the same time a same increment of negative sphere power to said fogging test value.
  • a negative sphere power for example equal to -0.25 diopters (D) is added to the current test value of each eye (block 202).
  • the one or more processors are programmed to perform a binocular visual acuity test (block 203), and iteratively add to both eyes a same increment of negative sphere power value as long as the visual acuity test indicates that the visual acuity is improved by said addition of an increment (arrow 204).
  • said negative increment of sphere power for example equal to -0.25 diopters (D) is iteratively added to the current test value of each eye (arrow 204) for both eyes at the same time.
  • the one or more processors are programmed to perform a double check of visual acuity with two different acuity charts of optotypes.
  • these sub-steps are repeated as long as the improvement of the visual acuity is over a predetermined threshold.
  • the addition of the negative increment is repeated as long as the subsequent binocular visual acuity test shows a gain of 1 letter or more, preferably of at least 2 letters out of 5 letters of the binocular visual acuity line and up to the maximum visual acuity is reached, that means until the visual acuity test indicates that the visual acuity does not improve anymore (arrow 205 of figure 2).
  • the one or more processors are programmed to undo the addition of the last increment of negative sphere power.
  • a positive sphere power equal to the opposite of the negative increment of sphere power is added, for example +0.25 diopters (D) is added to the current test value of each eye (block 206).
  • the one or more processors are programmed to determine a current value of binocular visual acuity of the eyes in said mesopic light conditions, until a maximum value of the mesopic binocular visual acuity is reached, corresponding to the binocular mesopic MPMVA power (Maximum Plus Maximum Visual Acuity power).
  • test value used in the step before the last step that does not lead to a visual acuity improvement is kept and constitutes the final current test value.
  • the final current test value then corresponds to the most convex sphere values allowing the best binocular visual acuity, that is to say the MPMVA, in mesopic light conditions.
  • the mesopic subjective refraction test is ended (block 206).
  • the one or more processors are then programmed to determine a mesopic raw value of the vision correction power for each eye of the individual, said mesopic raw value of the vision correction power being equal to the test value of the vision correction power associated to the maximum value of the mesopic binocular visual acuity.
  • the one or more processors may be programmed to perform, in mesopic light conditions, a binocular mesopic visual acuity test with the mesopic raw value of the vision correction power just determined and compare it with the binocular mesopic visual acuity test implemented at the beginning of the present step d) determined in step a), with the photopic value of the vision correction power determined in step a).
  • the difference is calculated by the processors and shows the improvement of acuity due to the mesopic raw value of the vision correction power.
  • the MPMVA power is here the mesopic raw value of the vision correction.
  • the individual may also visualize the difference between the vision correction provided by the photopic and mesopic values of vision correction power.
  • the one or more processors are programmed to display on the screen an image in mesopic light conditions and to control the optical units so as to provide the individual : first with the vision correction power determined in photopic conditions in step d) and second with the mesopic raw value of the vision correction power determined in mesopic conditions.
  • An example of the image displayed in mesopic light conditions is shown on figure 5.
  • Said mesopic value of said vision correction power is determined by said one or more processors based on said mesopic raw value of the vision correction power
  • said one or more processors are programmed to determine a refined mesopic value of said vision correction power based on said mesopic raw value of the vision correction power.
  • said refined mesopic value of said vision correction power is set as equal to said mesopic raw value of the vision correction power.
  • the refined mesopic value of said vision correction power then constitutes the mesopic value of the vision correction power looked for.
  • the one or more processors may be programmed to perform, after the mesopic subjective refraction test described above, a mesopic visual appreciation test with the following steps, shown schematically on figure 4:
  • determining said refined mesopic value of vision correction power for each eye of the individual by adding a refining value of spherical power to said mesopic raw value of the vision correction power for each eye, aiming at improving the quality of mesopic vision and depending on said predetermined negative value of spherical power (blocks 310, 311 , 312, 313 of figure 4).
  • the refining value of spherical power added by said one or more processors comprises one of the following:
  • this mesopic appreciation test is conducted in mesopic light conditions, by comparing the visual quality of the individual looking at the mesopic visual test image with high contrast and low luminance, for example 1 cd/m 2 with and without a binocular addition of -0.25D to the mesopic raw value of the vision correction power.
  • Said one or more processors are programmed to request and collect the answer of the individual (block 302).
  • This answer may be among the following:
  • the one or more processors are programmed to perform actions according to a decision tree.
  • An example of such a decision tree is shown on figure 4.
  • said comparison shows a difference in the visual performance of the eyes of the individual, either in favor of the vision with said added predetermined negative value of spherical power (arrow 302A) or in favor of the vision without said added predetermined negative value of spherical power (arrow 302B)
  • said one or more processors are additionally programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important (blocks 303 and 304 of figure 4).
  • the one or more processors are programmed to request and collect the answer of the individual asked to qualify the difference of visual performance with and without said added predetermined negative value of spherical power among the following possibilities: slight, moderate or important (blocks 303 and 304).
  • said one or more processors are programmed to add the refining value of spherical power equal to said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power (block 305).
  • Said one or more processors are programmed to determine said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power as being equal to a fraction of the absolute value of said predetermined negative value of spherical power.
  • the said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power is equal to half of the absolute value of the predetermined negative value of spherical power. It is then equal to +0.125 D.
  • Said one or more processors are then programmed to determine said refined mesopic value of vision correction power for each eye of the individual as equal to said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power added to said mesopic raw value of the vision correction power determined in step d) for each eye (block 310 of figure 4).
  • said one or more processors are programmed to add the refining value of spherical power equal to said null value (block 306 of figure 4).
  • Said one or more processors are then programmed to determine said refined mesopic value of vision correction power for each eye of the individual as equal to said mesopic raw value of the vision correction power determined in step d) for each eye (block 311 of figure 4).
  • said one or more processors are programmed to add the refining value of spherical power equal to said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power (block 307).
  • Said one or more processors are programmed to determine said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power as being equal to a fraction of the predetermined negative value of spherical power.
  • said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power is equal to half of the predetermined negative value of spherical power. It is then equal to -0.125 D.
  • Said one or more processors are then programmed to determine said refined mesopic value of vision correction power for each eye of the individual as equal to said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power added to said mesopic raw value of the vision correction power determined in step d) for each eye (block 312 of figure 4).
  • said one or more processors are programmed to add the refining value of spherical power equal to said predetermined negative value of spherical power (block 308).
  • Said one or more processors are then programmed to determine said refined mesopic value of vision correction power for each eye of the individual as equal to said predetermined negative value of spherical power added to said mesopic raw value of the vision correction power determined in step d) for each eye (block 313 of figure 4).
  • Said optometry system may moreover comprise a communication device for sending said refined mesopic value of the vision correction power to a manufacturing unit for ophthalmic lenses providing said mesopic value of the vision correction power to be manufactured.
  • said optometry system is part of a manufacturing system comprising a manufacturing line comprising a manufacturing device for manufacturing ophthalmic lenses and said manufacturing device is controlled by said one or more processors to manufacture an ophthalmic lens providing a refraction power equal to said refined mesopic value of the vision correction power.
  • the one or more processors may be programmed to successively provide the individual with the refined mesopic value of the vision correction power determined in step e) and the photopic value of vision correction power determined in step a), in mesopic light conditions, in order for the individual to be able to compare and visualize the gain in visual performances (acuity, comfort, clarity of vision... ) provided by the refined mesopic value of the vision correction power in mesopic light conditions compared to the visual performances obtained in the same mesopic light conditions but with a photopic value of vision correction power.
  • said one or more processors are programmed to determine, in an optional final sub-step e), a binocular visual acuity of the eyes, each eye being provided with the corresponding photopic value of the vision correction power determined in step a).
  • each eye being provided with the corresponding photopic value of the vision correction power determined in step a), just after having provided each eye with the mesopic value of the vision correction power determined in the current step e), allows to ensure that both visual acuities are determined after almost a same dark adaptation time in mesopic light conditions and therefore allows a better comparison one another.
  • the individual may also visualize the difference.
  • the one or more processors may be programmed to display on the screen an image in mesopic light conditions with a line of Sloan letters of typical EDTRS chart or other typical acuity optotypes with an achromatic grey background of mesopic luminance, an example of which is shown on figure 5, and to control the optical units so as to provide the individual firstly with the photopic value of vision correction power determined in photopic conditions in step d), and, secondly, with the refined mesopic value of the vision correction power determined in mesopic conditions.
  • the refined mesopic refraction shift may be determined under different light environments, for example in two mesopic light environments simulating respectively bad-lit roads and moderate-lit roads at night.
  • night driving light environment is dynamic, covering a wide luminance range.
  • road lighting at night can be classified in six levels from well-lit roads (luminance average 2 cd/m 2 ) as urban roads or highways with high traffic, and bad-lit roads (luminance average 0.3 cd/m 2 ) as secondary roads or highways with low traffic.
  • the refined mesopic refraction shift produced from photopic conditions and the associated change in visual acuity might be different according to change in night road lighting where people are driving. This is the reason why the refined mesopic refraction shift will preferably be measured under two mesopic luminance levels (medium and low mesopic optotype’s luminance level).
  • two different background luminances of the visual optotypes can be used to assess refined mesopic refraction shift and visual acuity shift produced from photopic to mesopic simulated night-driving light conditions: a first moderate mesopic luminance value to simulate a moderate-mesopic level (1 cd/m 2 for example) simulating moderate-lit roads at night, and a second low mesopic luminance to simulate a low-mesopic level simulating low-lit roads at night (0.36 cd/m 2 for example).
  • a single mesopic luminance test might be used for measuring the refined mesopic refraction shift. If only one mesopic level was to be chosen to assess the refined mesopic refraction shift compared to photopic value, the preferred mesopic level would be the moderate-mesopic level (for example 1 cd/m 2 ) as the visual acuity dispersion is lower for a test with a luminance of moderate mesopic level than for a test with a luminance of low mesopic level.
  • the moderate-mesopic level for example 1 cd/m 2
  • the preferred mesopic luminance level to assess the refined mesopic refraction shift is the moderate mesopic level.
  • a single mesopic refraction test is performed with a mesopic luminance to measure said refined mesopic refraction shift.
  • Figure 7 shows a Bland-Altman’s plots of agreement in refined mesopic refraction shift between the results of two mesopic refraction tests performed with two different background luminances : a moderate mesopic luminance of 1.1 cd/m2 and a low mesopic luminance of 0,36cd/m2.
  • the line noted “Bias” is the average difference between the refined mesopic refraction shifts measured with the two test background luminances.
  • the 95% limits of agreement “LoA” corresponds to almost 2 standard deviation (SD) from the average difference, more precisely equal to 1.96 SD, from the average difference between the refined mesopic refraction shifts measured with the two test background luminances.
  • Bland-Altman plots are extensively used to evaluate the agreement among two different instruments or two measurements techniques. Bland-Altman plots allow identification of any systematic difference between the measurements (i.e., fixed bias) or possible outliers. The 95% limits of agreement for each comparison (average difference ⁇ 1.96 standard deviation of the difference), give indications about how far apart the shifts measured by the two tests were more likely to be for most test subjects.
  • the visual acuity of the individual provided with a same vision correction power may vary when the light conditions vary from photopic to mesopic light conditions.
  • Figure 8 shows the visual acuity shift measured with different light conditions and different values of spherical power of a test lens placed in front of the eye of the individual.
  • the two results represented on the left side of the graph correspond to the visual acuity shifts measured with moderate mesopic luminance of the test background equal to 1 .1 cd/m 2 and low mesopic luminance of the test background equal to 0,36cd/m 2 while the individual is provided with a test lens having optical features corresponding to the photopic value of vision correction of the individual (marked as “w/photopic Rx”).
  • the visual acuity of the individual decreases additionally by one line with the lower test luminance compared to the moderate test luminance.
  • the two results represented on the right side of the figure correspond to the visual acuity shifts performed with moderate mesopic luminance of the background equal to 1 .1 cd/m 2 and low mesopic luminance of the background equal to 0,36cd/m 2 while the individual is provided with a test lens having optical features corresponding to the mesopic value of vision correction power of the individual.
  • the refined mesopic refraction shift is compensated.
  • the visual acuity of the individual additionally increases by 0.05 logMAR units (half of a VA line) is higher with the lower test luminance compared to the moderate test luminance. Higher dispersion of visual acuity is observed with the lower test luminance.
  • the use of two mesopic luminances in the assessment of the refined mesopic refraction shift might be used to subjectively test visual acuity loss occurring with the photopic value of vision correction power and visual acuity gain produced with the mesopic value of the vision correction power determined in low mesopic light conditions and moderate mesopic light conditions.
  • the displaying interface at the disposition of the expert testing the subject with the optometry device according to the invention could be controlled so as to disclose in addition to the information and datas relative to the refraction determination, and/or relative to the patient, a reproduction of the test image currently displayed for the subject, and for compact optometry device, a reproduction of the scene image if present, so as to ensure the display of the proper image luminance for the current lighting condition of the pending step of the protocol.
  • said one or more processors may additionally be programmed to perform a step of evaluation of the visual performances of the individual while his eyes are placed in light conditions ensuring mesopic vision and provided either with the photopic value of the vision correction power determined in step a) or with the mesopic value of the vision correction power determined in step e).
  • said one or more processors may be programmed to further perform a step of evaluation of the visual performances on mesopic contrast sensitivity when provided either with the photopic value of the vision correction power determined in step a) or with the mesopic value of the vision correction power determined in step e).
  • the test image may show optotypes on a background with a lower contrast than the contrast of the test image shown during the mesopic value determination of step e), for example at low or very low contrast conditions.
  • the device can be programmed to implement a contrast sensitivity test.
  • this test can involve a mesopic contrast sensitivity test image comprising:
  • a background with mesopic luminance for example between 0.005 to 5 cd/m2 and more preferably 1 cd/m2
  • the contrast value is determined as being the lowest one at which the subject is able to read for example 3 optotypes out of 5.
  • the device can be programmed to implement a contrast acuity test. Accordingly, as disclosed in the Figures 17 and 18, this test can involve a mesopic contrast acuity test image comprising:
  • mesopic contrast acuity test images having same mesopic background luminance and different mesopic optotypes luminance, in order to achieve optotype/background contrasts between 100% and 10%, more preferably of 40%.
  • said one or more processors may be programmed to further perform a step of evaluation of the visual performances on glare sensitivity when provided either with the photopic value of the vision correction power determined in step a) or with the mesopic value of the vision correction power determined in step e).
  • the screen showing the test image is equipped with light sources and the one or more processors may be programmed to turn on said light sources so as to simulate a glare situation, while providing the subject either with the photopic value of the vision correction power determined in step a) or with the mesopic value of the vision correction power determined in step e).
  • the optometry device can disclose in the pictures displayed by the screen and/or provide directly or indirectly, additional lighting spots imitating the kind of disturbing lights encountered at night (moon light, street lights, headlights of cars traveling in the opposite direction and/or reflecting in the side or inner rear mirror of a car... ) so as to test the level of discomfort of the subject or the performance reached by the specific correction brought by the refraction unit.
  • such light source(s) can be brought by a specific light source such as a LED, or LED strip(s).
  • This light source may be:
  • o fixed inside the casing o fixed on an inner wall of the casing on the optical path seen by the observer directly or further to a reflection on a mirror or beam splitter, o fixed on the scene screen’s edge (for example on the scene screen’s edge(s), i.e. around the background picture displayed by the scene screen), and/or o fixed on the test screen ’s edge (for example on the test screen’s edge(s), i.e. around the test image displayed by the test screen, the light source being integrated in the image observed by the subject when the scene image and the test image provided by the test screen are superimposed.
  • This light source may be fixed so as to define moving light(s) such as lights of a moving car
  • the light source can comprise LEDs strips that could be fixed on the test screen edges and each LED could be individually controlled so as to define when the test image is superimposed with a scene image defined accordingly, a dynamic and apparently moving lighting simulating for example lights of a car moving toward the subject in a highway background.
  • a fixed and powerful LED could be fixed on the test screen’s edge so as to define when the test image is superimposed with a scene image defined accordingly, a powerful lighting such as a street lamp or a dazzling lighting appearing in the inner or lateral mirror of a car.
  • the device can be programmed to implement a glare sensitivity test to measure subjectively the benefit of the mesopic vision correction (step e) on discomfort on a glare simulated situation, compared to photopic vision correction.
  • the subject can look at a night simulated scene (may integrate mesopic visual acuity test pannel or contrast acuity pannel).
  • the types of glare can involve: fixed light sources on the edge of screens (one, two or all sides) simulating streetlights or car’s headlights from the left or right side on the road, dynamic glare sequence simulating dynamic glare from car’s headlights, a single LED or several LEDs,
  • LED s spectrum might variate to measure different sensibility (Cold white LED, warm white LED, red LEDS... ) and/or have a temporality: intermittent LED’s simulating bycicles LEDs.
  • the overall protocol sequence can involve:
  • mesopic contrast visual performance evaluation (contrast acuity or contrast sensitivity) to show the benefit of mesopic correction on contrast vision
  • the visual performances of the individual are assessed either thanks to a comparison of the individual’s feedbacks or of the binocular visual acuities determined respectively between the vision correction power determined in step a) or with the mesopic vision correction power determined in the step e).
  • This assessment allows to receive the individual’s subjective feedback in mesopic light conditions about the benefit of the mesopic vision correction over the photopic vision correction in mesopic light conditions.
  • the optometry system of the invention described above allows implementing the method of the invention for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions, using an optometry device having a refraction test unit with two optical refraction elements, each optical refraction element being adapted to provide test values of said vision correction power to one of the eyes of the individual, said method comprising the following steps: a) determining a photopic value of said vision correction power of said corrective lens for each eye of said individual by achieving a photopic subjective refraction test in light conditions ensuring photopic vision of the eyes of the individual, b) placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time, c) placing the eyes of the individual in light conditions ensuring mesopic vision of the eyes of the individual and d) achieving a mesopic subjective refraction test, said mesopic subjective
  • a method for manufacturing an ophthalmic lens adapted to correct the vision of a individual may comprise the step of implementing said method for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions according to the invention and a step of manufacturing said ophthalmic lens such that it presents said mesopic value of the vision correction power.
  • the optometry system and method of the invention provides a mesopic value of vision correction power for the eyes of the individual, based on a subjective test performed in mesopic light conditions comprising exclusively binocular steps. This provides a quick and reliable mesopic value of vision correction power.
  • the mesopic appreciation test optionally performed in step e) provides a better accuracy by refining mesopic vision correction in 0.125D steps leading to visual performance improvement.
  • the invention allows taking into account and correcting the loss of visual acuity due to decrease in luminance (from photopic to mesopic) and the shift of subjective refraction in 0.125D steps, resulting in a gain of visual acuity, contrast sensitivity and quality of vision with the refined mesopic value of the vision correction power. It is especially useful to provide the individual with a vision correction equipment comprising ophthalmic lenses with said refined mesopic value of the vision correction power for night driving conditions.
  • the method of the invention was applied with the optometry system of the invention, with a predetermined amount of time of 5 minutes in step b) by using a precise refraction in photopic light conditions by means of a phoropter based on continuously variable power which allow power steps of 0.01 D.
  • the amount of time defined in step b) is called in the following the “dark adaptation time”.
  • a significant average visual acuity loss of 2 lines of EDTRS chart was recorded when light conditions were changed from photopic to mesopic light conditions while the subjects wore ophthalmic lenses with photopic value of the vision correction power, as shown on figure 9.
  • a significant average visual acuity improvement of 1 line of EDTRS optotypes was recorded in mesopic light conditions when the subject switched to ophthalmic lenses having said mesopic value of the vision correction power determined with the optometry system and method according to the invention.
  • figure 10 shows values of mesopic visual acuity shifts (VA Shift) measured when changing the light conditions from photopic to mesopic light conditions, while the individual is provided with the photopic value of vision correction power (w/STD Rx) on the left side of figure 10, and measured when changing the value of vision correction power from photopic to mesopic value of vision correction power while the individual is placed in mesopic light conditions (w/NIGHT Rx), on the right side of figure 10.
  • VA Shift mesopic visual acuity shifts
  • the logMAR visual acuity shift measured when changing the light conditions from photopic to mesopic light conditions is 0.19, implying a loss of two lines of visual acuity, whereas, with mesopic light conditions, the logMAR visual acuity shift is -0.06 when changing the value of vision correction power from photopic to mesopic value of vision correction power, implying a gain of one line of visual acuity.
  • step b) of the method according to the invention was also evaluated when the subject is exposed to scotopic light conditions.
  • the method of the invention was applied with the optometry system of the invention, with two predetermined amounts of dark adaptation time of 2.5 minutes and 5 minutes in step b), the dark adaptation times being randomized.
  • the mesopic refraction protocol was used under the two above mentioned dark adaptation times randomly, at the same visit.
  • the test luminance was moderate at 1 .1 cd/m2.
  • a re-adaptation time to photopic light levels was conducted between dark adaptation times to ensure same retinal adaptation state before starting the mesopic refraction.
  • the results obtained with the two different dark adaptation times were compared.
  • the 82 subjects comprised 50 non-presbyopes persons and 32 presbyopes persons.
  • the same refraction test unit was used with 1.1 cd/m2 mesopic visual optotype background luminance.
  • the dark adaptation time is the only variable parameter for this comparison.
  • Figure 13 shows the visual acuity gain in mesopic light conditions due to compensation of refined mesopic refraction shift at two dark adaptation times, 5-min (left side) and 2.5min (right side).
  • the subjects were provided with a test lens having a mesopic value of vision correction power.
  • the mean visual acuity gain is 0.06 logMAR (about 1 visual acuity line of ETDRS chart). No significantly difference is observed between the visual acuity gains measured with the two different dark adaptation times (p>0.05).
  • the mean value of the refraction shift is -0.36 D with a standard deviation (SD) of 0,21 D
  • the median value of the refraction shift is -0.25 D with an interquartile range of 0.25 D
  • the range is -0.87 to 0.125D.
  • the mean value of the refraction shift is -0.37 D with a standard deviation (SD) of 0,23D
  • the median value of the refraction shift is -0.37 D with an interquartile range of 0.25 D
  • the range is -0.87 to 0.125D.
  • the p-value of 0.89 shows that the refraction shift obtained with a 2.5 min time dark adaptation and a 5 min time dark adaptation are not significantly different.
  • the visual acuity gain is also of about one line.
  • the median value of the visual acuity gain with dark adaptation time of 5 min is -0.05 logMAR units.
  • Figure 12 shows a Bland-Altman's plots of agreement in refined mesopic refraction shift between two dark adaptation times, 5 min and a 2.5 min.
  • “Bias” is the average difference between both dark adaptation times and the 95% limits of agreement (LoA) is almost 2 SD from the average difference, more precisely 1.96 standard deviation.
  • the following table illustrates the different groups of refined refraction shifts obtained in a sub-population of subjects taken from the clinical study described above.
  • the refraction shifts of 54 healthy and regular drivers (non presbyobes) included in the above mentioned study are determined using a dark adaptation time of 5 minutes. They include 38 women and 16 men.
  • Drivers rated better the lenses with mesopic value of vision correction power for visual tasks such as reading road signs, perception of light sources, judgement of road exit distances or judgement of distances with another vehicle, i.e. all of their visual tasks more related to central vision than to peripheral vision.
  • Drivers also reported better global and far vision as well as satisfaction during their night driving activity.
  • Reproducibility refers to the variability of the mesopic subjective refraction over time and this variability is related to many factors such as examiner performing the measurement, time past between measurements or time day (for instance day versus afternoon). Reproducibility is a measurement of precision or closeness agreement and whether over time a given method of measurement accurately measures what it aims to measure. Good reproducibility of a given methodology, for example a subjective refraction protocol, is used to validate said methodology. Reproducibility measurement is usually reported as the mean difference between measurements over time and the 95% limits of agreement which represents the distribution of difference between measurements and thus, the probability that 95% of difference fall within a range.
  • the mean differences calculated between two repeated measurements V1 and V2 over the time of mesopic refraction shift according to the invention, as illustrated on the figure 14, is -0.05 D and 95% limits of agreement is ⁇ 0.28 D. 95% of differences between the two measurements V1 and V2 over time fall within +0.23 D and -0.33 D.
  • LoA is the 95% limits of agreement which is about two standard deviations from average difference, here 1.96 SD.
  • the mesopic refraction determination method according to the invention has been proven to be reproducible over time independently from the operator performing the subjective refraction determination or from the time past between two measurements.
  • the invention also concerns any optical article designed such as to define a vision correction equals to the mesopic value of vision correction power determined with the optometry system and method according to the invention.
  • Said optical article can possibly include also a filter and/or an anti reflective coating known to be suited to improve an individual’s vision in mesopic lighting conditions and/or reduce glare.
  • said optical article can comprise, in addition to the vision correction equals to the mesopic value of vision correction power determined with the optometry system and method according to the invention, any one of the following features considered alone or in combination:
  • said antireflective coating on said front and rear faces has a luminous reflectance in the visible region for scotopic vision Rv' lower than or equal to 1 .0%, preferably lower than or equal to 0.7%, more preferably lower than or equal to 0.5%,
  • said antireflective coating being as defined in table 2 below and as described in EP3629079 (Refractive indices are expressed at 25°C at a wavelength of 550 nm)
  • CutLED being defined by:
  • CutLED 100 where Z is a discrete or continuous sum operator, A is the wavelength in nm, lens T% is the transmittance of said lens in % and LED emission% is the spectral distribution of a white light emitting diode in %,
  • the lens contains light absorbing dyes, more preferably, it comprises a substrate and said light absorbing dyes are located in the mass of said substrate, or in a thin layer of the mass of the substrate of the lens.
  • Light cut behavior is mainly achieved through absorption with absorbing dyes deposited through an imbibition or a sublimation method, wherein the tinting recipe is balanced to achieve the desired value of CutLED while maintaining sufficiently high transmittance Tv and a sufficiently neutral colour.
  • dyes are deposited by sublimation on lens substrates with a mixture of three sublimable dyes (blue, yellow and red to yield a brown colour) printed on a specific paper, dyes being transferred from the specific paper to the concave side of the lens by sublimation, the lens being finally heated so that dyes diffuse in the mass of the lens (imbibiting step), ideally with the resulting optical properties as disclosed in the below Table 3.
  • the optical article can be as described in the embodiment L3 or L4 of EP3629079, with optical properties as disclosed in the Table 3.
  • the invention furthermore concerns any set of optical articles including a first optical article designed such as to define a vision correction equals to the photopic vision correction, and a second optical article according to the invention.
  • such a set of optical articles can include for example a first optical article such as an ophthalmic lens designed with the photopic vision correction power, and a second optical article such as an ophthalmic lens designed with the refined mesopic vision correction power, optionally comprising an antireflective coating and/or a tint as defined previously.
  • the second optical article can consist in a clip adapted to be removably associated with the first optical article and to define with the latter a global vision correction that equals to the refined mesopic value of vision correction, the clip associated with each eye of the individual being designed with a sphere calculated or equal to the corresponding refined mesopic shift determined thanks to the system and method according to the invention.
  • a vision correction lens or set of optical articles may then be manufactured with said mesopic vision correction power.

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Abstract

The invention relates to such an optometry system comprising a computer with one or more processors programmed to: a) control the optometry device to determine a photopic value of said vision correction power of said corrective lens for each eye of said individual by achieving a photopic subjective refraction test in photopic vision, or to retrieve an initial vision correction value stored in a memory of the optometry system, or to collect an initial vision correction value, b) validate a step of placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for an amount of time, c) validate a step of placing the eyes of the individual in light conditions ensuring mesopic vision of the eyes of the individual and d) control the optometry device to achieve a mesopic subjective refraction test comprising: - fogging both eyes with a predetermined fogging spherical power, - iteratively adding to both eyes a same negative predetermined value ofspherical power to said fogging test value and determining mesopic binocular visual acuities of the eyes until a maximum value of the mesopic binocular visual acuity is reached, thereby determining for each eye a mesopic raw value of the vision correction power, e) determining said mesopic value of vision correction power based on said mesopic raw value of the vision correction power.

Description

TITLE: OPTOMETRY SYSTEM FOR DETERMINING, FOR EACH EYE OF AN INDIVIDUAL, A MESOPIC VALUE OF A VISION CORRECTION POWER OF A CORRECTIVE LENS
TECHNICAL FIELD OF THE INVENTION
The invention relates to an optometry system for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens.
BACKGROUND INFORMATION AND PRIOR ART
In order to provide visual equipment adapted to the visual defect of an individual, it is necessary to assess this visual defect and determine the features of an equipment adapted to correct it.
In practice, an individual’s vision may be tested during a subjective test protocol, using a phoropter allowing placing successively in front of his eye lenses to provide different test values of said vision correction power to each of the eyes of the individual.
This test protocol may be achieved using a classical phoropter or a phoropter having lenses of continuous variable power.
At each trial of the subjective test, corresponding to a current lens power placed in front of his eye, the individual is asked to express a visual assessment that corresponds to an indication of a preferred visual state among two visual states presented to him or if he cannot decide between the two. The two visual states may correspond to his vision of two different images through the current lens power or may correspond to his vision through the previous lens power and his vision through the current lens power, for example.
Many protocols for achieving such a subjective test are known. However, most of them are established and performed in photopic light conditions.
Even though there is disparity in reported values in literature about the three ranges of light conditions and in particular for the mesopic range, last values have been established in 2010 by the CIE (International Commission on Illumination) in report CIE 191 :2010 titled “Recommended systems for mesopic photometry based on visual performance technical report”.
Photopic light conditions correspond to the conditions experienced in daylight or with other bright light, where vision is believed to involve mainly the cones of the retina. They may be defined as a range of high light levels above rod saturation where vision is mediated by signals from cone photoreceptors. Photopic light conditions implying photopic vision of the eye correspond to a luminance strictly over 5 cd/m2 at eye level according to CIE 191 :2010 “Recommended system for mesopic photometry based on visual performance technical report”.
Scotopic light conditions correspond to the conditions experienced at night, with very low level of luminance. Scotopic vision is produced exclusively through rod cells, which are most sensitive to wavelengths of around 498 nm (bluegreen) and are insensitive to wavelengths longer than about 640 nm (red-orange). Scotopic light conditions are typically below 0.005 cd/m2 in luminance at eye level according to the last CIE 191 :2010 “Recommended system for mesopic photometry based on visual performance technical report”.
Mesopic light conditions correspond to the conditions experienced between twilight with low level of luminance and night. They may be defined as a range of intermediate light levels between cone threshold and rod saturation where both rod and cone signals contribute to a visual response. Mesopic vision is therefore a combination of photopic and scotopic vision with cones and rods involved. Moreover, the respective contribution of cones and rods can vary within the mesopic range. Mesopic light conditions range approximately from 0.005 to 5.0 cd/m2 in luminance at eye level.
Most nighttime outdoor and street light conditions are in the mesopic light range.
The vision correction powers determined during above mentioned photopic subjective tests are therefore adapted to correct the visual defects of the eyes of the individual in photopic light conditions.
However, changing the light environment from photopic to mesopic light conditions may involve a refraction shift. This is especially experienced by individuals during night driving. This refraction shift is commonly called “night myopia”.
This refraction shift may not be assessed through most currently used protocols of subjective refraction tests.
SUMMARY OF THE INVENTION
Therefore one object of the invention is to provide a new optometry system adapted to perform a subjective refraction in mesopic conditions.
The above objects are achieved according to the invention by an optometry system for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions, said system comprising an optometry device having a refraction test unit with two optical refraction elements, each optical refraction element being adapted to provide test values of said vision correction power to one of the eyes of the individual, said optometry system comprising a computer with one or more processors programmed to: a) control the optometry device to determine a photopic value of said vision correction power of said corrective lens for each eye of said individual by achieving a photopic subjective refraction test in light conditions ensuring photopic vision of the eyes of the individual or to retrieve an initial vision correction value stored in a memory of the optometry system, or to collect an initial vision correction value, b) validate a step of placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time, c) validate a step of placing the eyes of the individual in light conditions ensuring mesopic vision of the eyes of the individual and d) control the optometry device to achieve a mesopic subjective refraction test, said mesopic subjective refraction test comprising:
- fogging both eyes by providing to each eye a fogging test value of vision correction power equal to a predetermined fogging spherical power added to the corresponding photopic value of the vision correction power,
- iteratively adding to both eyes a same negative predetermined value of spherical power to said fogging test value and determining, each time said negative predetermined value of spherical power is added, a mesopic binocular visual acuity of the eyes until a maximum value of the mesopic binocular visual acuity is reached, thereby determining for each eye a mesopic raw value of the vision correction power equal to a test value of the vision correction power associated to the maximum value of the mesopic binocular visual acuity, e) determining, for each eye of the individual, said mesopic value of vision correction power based on said mesopic raw value of the vision correction power.
Thanks to the optometry system of the invention, it is possible to determine said mesopic correction power in a quick and reliable manner.
This is obtained in particular through the use of one or more processors programmed to perform a binocular sphere refraction test in mesopic light conditions. The subjective test is quickly performed.
Other advantageous non limiting features of the system according to the invention are listed hereafter:
- said one or more processors are programmed to perform, in step e), a final mesopic visual appreciation test with the following steps:
- controlling the optometry device for providing each eye of the individual with the mesopic raw value of the vision correction power determined in step d),
- for each eye, controlling the optometry device for adding a predetermined negative value of spherical power to said mesopic raw value of the vision correction power and collecting an answer of the individual asked to compare his visual performance with and without the added predetermined negative value of spherical power,
- based on this comparison, determining said mesopic value of vision correction power for each eye of the individual by adding a refining value of spherical power to said mesopic raw value of the vision correction power for each eye, aiming at improving the quality of mesopic vision and depending on said predetermined negative value of spherical power ;
- the refining value of spherical power added by said one or more processors comprises one of the following :
- said predetermined negative value of spherical power,
- a positive or negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power
- a null value ;
- when said comparison shows no difference in the visual performance of the eyes of the individual, said one or more processors are programmed to add the refining value of spherical power equal to said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power ;
- when said comparison shows a difference in the visual performance of the eyes of the individual, said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and when said answer indicates a slight or moderate difference in the visual performance of the eyes of the individual in favor of his visual performance with the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power ;
- said one or more processors are programmed to determine said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power as being equal to a fraction of the predetermined negative value of spherical power ;
- when said comparison shows a difference in the visual performance of the eyes of the individual, said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and when said answer indicates an important difference in the visual performance of the eyes of the individual in favor of his visual performance with the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said predetermined negative value of spherical power ;
- when said comparison shows a difference in the visual performance of the eyes of the individual, said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and when said answer indicates a slight or moderate difference in the visual performance of the eyes of the individual in favor of his visual performance without the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said null value ;
- when said comparison shows a difference in the visual performance of the eyes of the individual, said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and when said answer indicates an important difference in the visual performance of the eyes of the individual in favor of his visual performance without the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power ;
- said one or more processors are programmed to determine said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power as being equal to a fraction of the absolute value of said predetermined negative value of spherical power ;
- said one or more processors are programmed to determine, in step d) or e), a binocular visual acuity of the eyes, each eye being provided with the corresponding photopic value of the vision correction power determined in step a) ;
- said one or more processors are programmed to perform a step of evaluation of the visual performances of the subject while his eyes are placed in light conditions ensuring mesopic vision and provided either with the photopic value of the vision correction power determined in step a) or with the mesopic value of the vision correction power determined in step e) ;
- it comprises an autorefractometer configured to determine, for each eye of said individual, a determined initial vision correction power value, and/or a memory storing for each eye a stored initial vision correction power value and/or an entry unit collecting for each eye a collected initial vision correction power value, and wherein, said one or more processors are programmed to perform a preliminary step to set an initial photopic value of said vision correction power in light conditions ensuring photopic vision of the eye of the individual, as being equal to said determined and/or stored and/or collected initial vision correction power value for each of the eyes of the individual ;
- said one or more processors are programmed to validate said step of placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual with said predetermined amount of time being comprised between 2 minutes and 10 minutes, more preferably between 2 minutes and 5 minutes, more preferably equals to 2.5 minutes;
- the optometry system comprises an input device for collecting the answers of the individual and wherein said one or more processors are programmed to set each next test value provided by said optical refraction element according to the last answer collected by said input device from the individual ;
- the optometry system comprises a screen adapted to display vision tests and wherein said one or more processors are programmed to control the luminance of the screen depending on the light conditions ensuring photopic, scotopic or mesopic vision in which the eyes of the individual are placed ; and
- it comprises a main casing enclosing the screen and to which the optometry device is mounted so as to allow the individual to see the screen through the optical refraction elements of the optometry device, and including an internal optical system allowing the observation of an image of the screen at several observation distances.
The invention also relates to a method for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic vision conditions, using an optometry device having a refraction test unit with two optical refraction elements, each optical refraction element being adapted to provide test values of said vision correction power to one of the eyes of the individual, said method comprising the following steps: a) determining a photopic value of said vision correction power of said corrective lens for each eye of said individual by achieving a photopic subjective refraction test in light conditions ensuring photopic vision of the eyes of the individual or to retrieve an initial vision correction value stored in a memory of the optometry system, or to collect an initial vision correction value, b) placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time, c) placing the eyes of the individual in light conditions ensuring mesopic vision of the eyes of the individual and d) achieving a mesopic subjective refraction test, said mesopic subjective refraction test comprising:
- fogging both eyes by providing to each eye a fogging test value of vision correction power equal to a predetermined fogging spherical power added to the corresponding photopic value of the vision correction power,
- iteratively adding to eyes a same negative predetermined value of spherical power to said fogging test value and determining, each time said negative predetermined value of spherical power is added, a mesopic binocular visual acuity of the eyes until a maximum value of the mesopic binocular visual acuity is reached, thereby determining for each eye a mesopic raw value of the vision correction power equal to a test value of the vision correction power associated to the maximum value of the mesopic binocular visual acuity, e) determining, for each eye of the individual, said mesopic value of vision correction power based on said mesopic raw value of the vision correction power.
The invention also relates to an optical article designed such as to provide a vision correction equal to the mesopic value of vision correction power determined with the optometry system and method according to the invention.
Said optical article can possibly also include a filter and/or an anti reflective coating known to be suited to improve an individual’s vision in mesopic lighting conditions and/or reduce glare.
The invention furthermore relates to a set of optical articles including a first optical article designed based on the mesopic value of vision correction power determined according to the invention, and a second optical article designed such as to provide a vision correction equal to the photopic vision correction.
More precisely, such a set of optical articles can include for example a first optical article such as an ophthalmic lens designed with the mesopic vision correction, and a second optical article such as an ophthalmic lens designed with the photopic vision correction. As an alternative, the first optical article can consist in a mesopic clip comprising ophthalmic lenses adapted to be removably associated with the second optical article. Each ophthalmic lens of said mesopic clip is designed to provide, in association with a corresponding lens of the second photopic optical article, a global vision correction that is equal to the mesopic vision correction. The ophthalmic lens of the mesopic clip associated with each eye of the individual is designed with a sphere calculated or equal to the corresponding mesopic refraction shift determined thanks to the system and method according to the invention, the mesopic refraction shift being equal to a difference between a (raw or refined) mesopic vision correction and a photopic vision correction.
DETAILED DESCRIPTION OF EXAMPLE(S)
The following description with reference to the accompanying drawings will make it clear what the invention consists of and how it can be achieved. The invention is not limited to the embodiment/s illustrated in the drawings. Accordingly, it should be understood that where features mentioned in the claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims.
In the accompanying drawings : - Figure 1 is a schematic view of an optometry system according to the invention,
- Figure 2 is a block diagram of steps of a subjective refraction test in photopic conditions implemented in an embodiment of step a) of the method according to the invention,
- Figure 3 is a block diagram of steps of a subjective refraction test in mesopic light conditions implemented in an embodiment of step d) of the method according to the invention,
- Figure 4 is a block diagram of steps of a visual appreciation test in mesopic light conditions implemented in an embodiment of step e) of the method according to the invention,
- Figure 5 is an example of a test image comprising a line of Sloan letters of typical EDTRS chart with an achromatic grey background of mesopic luminance,
- Figure 6 is a graph showing the refraction shift determined for two different test background luminance, the refraction shift being in this graph, equal to a difference between a refined mesopic vision correction and a photopic vision correction, the dark adaptation time being 5 minutes and the number of test subjects being 36,
- Figure 7 is a Bland-Atman plot showing the difference between the refined mesopic refraction shifts determined through mesopic refraction tests using test images having a background luminance of 0.36 and 1.1 cd/m2 as a function of the mean mesopic refraction shift determined for the corresponding tests, the dark adaptation time being 5 minutes and the number of test subjects being 36,
- Figure 8 is a graph showing visual acuity shifts determined in mesopic light conditions while using test images having a background luminance of 0.36 or 1.1 cd/m2 and providing the individual with lenses exhibiting a vision correction power equal to a photopic value of vision correction power (referenced as “w/photopic Rx” on figure 8) or to a mesopic value of vision correction power (referenced as “w/mesopic Rx” on figure 8),
- Figure 9 shows schematically visual acuity variations of an individual tested in different light conditions and with a photopic refraction test (referenced as “regular refraction” or “photopic Rx” on figure 9) or to a mesopic refraction test (referenced as “mesopic Rx” on figure 9),
- Figure 10 is a graph showing (left: “w/photopic Rx”) visual acuity shifts observed when light conditions go from photopic to mesopic light conditions while the individual wears the photopic vision correction and (right: “w/mesopic Rx”) visual acuity shifts observed when the individual wears from the photopic vision correction to the mesopic vision correction, while light conditions remains mesopic light conditions, the number of test subjects being 96, all presenting a Rx shift,
- Figure 11 is a graph showing refraction shifts values measured between two successive mesopic refraction tests according to the invention comprising each a photopic light conditions step, a dark adaptation step, and a mesopic light conditions step, the two successive mesopic refraction tests being separated by a re-adaptation period to photopic light conditions in order to ensure retinal adaptation state before the second mesopic refraction test, and having two different times of (left) 5 minutes and (right) 2.5 minutes of dark adaptation step ,the dark adaptation time of the first mesopic refraction test being randomly set to 5 minutes or 2.5 minutes so as to avoid in the results obtained, an effect of the order in which the lowest dark adaptation time is used in the first or the second mesopic refraction test, the number of test subjects being 82,
- Figure 12 is a Bland-Atman’s plot showing the difference between the refraction shifts determined with tests involving different dark adaptation times (2.5 and 5 minutes) as a function of the mean refraction shift determined for the corresponding tests, the dark adaptation times of the mesopic refraction tests being randomly set as for the figure 11 and for the same reasons, and the number of test subjects being 82,
- Figure 13 is a graph showing visual acuity shifts determined in mesopic light conditions, the individual being provided with lenses exhibiting a vision correction power equal to a mesopic value of vision correction power (NIGHT Rx) when using a dark adaptation time of 2.5 or 5 minutes, the dark adaptation times being randomly set as for the figure 11 and for the same reasons,, the number of test subjects being 82, all presenting a Rx shift with both dark adaptation times,
- Figure 14 is a Bland-Altman's plot showing the difference between the refined mesopic refraction shifts determined at two different times V1 and V2 for testing reproducibility of the method according to the invention, difference between visit 1 and visit 2 (V1 & V2) being on average 60 days; the number of test subjects being 54, all non-presbyopes, 1.1 cd/m2 test luminance and 5-min dark adaptation time, showing agreement in refined Rx shift between visit 1 & 2, - Figure 15 shows a distribution and mean values of refined Rx shift in diopters (D) measured under 5-min dark adaptation time and 1.1 cd/m2 test luminance conditions; the number of test subjects being 115 (82 non-presbyopes and 33 presbyopes)
- Figures 16, 17 and 18 show test images comprising lines of Sloan letters of typical EDTRS chart with an achromatic grey background of mesopic luminance.
The invention principally relates to an optometry system for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions according to a method of the invention.
The optometry system allows determining said mesopic value of the vision correction power of the corrective lens with the purpose of manufacturing this corrective lens to be mounted in a vision correction equipment used by said individual.
Said optometry system is configured to implement a subjective refraction determination at several observation distances, including and preferably far distance, but also possibly intermediate and near distance.
Such optometry system comprises a screen to display an eye chart to be observed by the individual, a phoropter (also called “refractometer”) designed for providing one test lens or multiple test lenses with different vision correction powers close to the eye of the individual, through which the individual observes an eye chart, the vision correction powers of the phoropter being changed according to the answers provided by the individual relative to its ability to see optotypes, for example characters, of the eye chart through the test lens providing a vision correction power.
Generally, the screen is placed at 5-6 meters from the phoropter to simulate an observation distance at the infinity, and the eye chart is displayed in a conventional examination room with controlled lighting conditions. The characters of the eye chart and the background of the characters have their own luminance. In this case, the individual observes the image displayed by the screen through the vision correction powers at an observation distance equal to the distance between the screen and the phoropter of 5-6 meters, which could be approximated to the infinity.
For smaller examination rooms, when the screen cannot be placed at 5-6 meters to approximate infinity, or for “compact optometry system” specifically designed to reproduce, in a compact version, an examination room, the screen is placed closer to the phoropter and an optical system allows defining a larger distance of observation than the physical distance separating the screen from the phoropter.
This is the case for the described embodiment, wherein the phoropter belongs to an optometry device having a casing or housing simulating an examination room. The casing or housing encloses a display unit suitable for displaying a test picture to be seen through the phoropter 100, placed at a short distance from the phoropter, but observed by the individual at several observation distances, thanks to an internal optical system.
Figure 1 shows a schematic view of an example of such an optometry system 10 for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions according to the invention.
Said optometry system 10 comprises an optometry device 20 having a refraction test unit 30 with two optical refraction elements 31 , each optical refraction element being adapted to provide different test values of said vision correction power to one of the eyes of the individual.
The optometry system 10 also comprises a display unit 40 adapted to produce a visual test image for the individual’s eye, said visual test image being visible through an exit aperture of said refraction test unit 30 of the optometry device 20.
The refraction test unit 30 is interposed between the display unit 40 and the individual’s eye. It is movable so that its position may be adjusted in front of the eyes of the individual.
Said refraction test unit 30 may be of any kind known to the man skilled in the art. Such refraction test unit 30 is usually called “phoropter”. It is adapted to provide a variable optical correction for the individual’s eye looking therethrough.
The optical refraction elements comprise for example a lens with variable power and an optical component with a continuously variable cylindrical power and axis. It comprises here a deformable liquid lens having an adjustable shape.
Alternatively, or in addition, the optical refraction element may comprise an ensemble of non-deformable lenses having different optical powers, and a mechanical system that enables to select some of these lenses to group them to form the set of lenses through which the individual can look. In this last case, to adjust the refractive power of the set of lenses, one or several lenses of the set of lenses are replaced by other lenses stored in the refraction test unit. The refraction test unit may also include a pair of independently rotatable lenses each having a cylindrical power.
The lens with variable power or the different test lenses are configured to provide the test values of said vision correction power.
The refraction test unit 30 optionally comprises one or more elements designed to receive the head of the individual and hold it in a predetermined position relative to the refraction test unit 30. This element may for example receive the forehead of the individual. Alternatively or in addition, the refraction test unit could comprise an element to receive the chin of the individual.
Such refraction test unit 30 is well-known and will not be described in more details here.
The light beam exiting the display unit 40 is directed through the lens or lenses of the refraction test unit 30 towards the eye of the individual.
The display unit 40 is adapted to produce both a visual test image and a scene image for the individual’s eye.
The visual test image is a virtual image formed by a projection optical system (and more precisely by a first projection sub-system which projects a visual test picture displayed on a visual test screen 41 (first screen) and by an optical element (if present as explained later), that optically transforms said visual test picture into the virtual visual test image.
The display unit 40 comprises:
- a screen 41 adapted to display vision tests,
- an internal optical system 42 allowing the observation of an image of the screen at several observation distances.
Said internal optical system 42 produces the visual test image observed by the individual through the refraction test unit 30 based at a variable distance from said exit aperture.
Alternatively, the optometry system may provide a visual test image at a fixed distance.
Preferably, the optometry system is configured to provide said visual test image at least at an observation distance of far vision from the eyes of the individual, for example at an observation distance equal or higher than 5 meters, preferentially 6 meters from the eyes of the individual.
Said vision tests typically comprise a test picture. The image of said test picture through said internal optical system 42 produces said visual test image.
Advantageously, the distance between said visual test image and said exit aperture, and thus the observation distance between the visual test image and the eye of the individual, may be varied, for example between an observation distance of far vision and a different observation distance of near or intermediate vision. An observation distance of far vision is generally considered to be above 5 to 6 meters, up to infinity. An observation distance of intermediate vision is generally considered as being comprised between 40 centimeters and 5 meters. An observation distance of near vision is generally conserved as being comprised between 40 and 33 centimeters.
In the example represented on figure 1 , the optometry device 20 according to the invention includes a casing 2 adapted to be placed on a table, for instance, or to be mounted on a stand to be placed on a table or on the floor.
The casing 2 encloses here the display unit 40 comprising the screen 41 and the internal optical system 42. The refraction test unit 30 is mounted on the casing 2.
The first screen 41 is for instance one of the following: a LED or OLED screen, a serigraphy with backlight screen, a display light projection screen with micro video projector, an LCD screen or a TFT screen. It produces a light beam along a screen axis S perpendicular to the mean plane of the screen 41 . This light beam is meant to produce an image of an object, such as an optotype, for an individual using the optometry device.
The test picture or image displayed by the screen 41 comprises a background and a visual target such as an optotype, for example Sloan letters or another type of letters, numbers, Landolt’s C or Snellen’s E or drawings. As an example, a test image may comprise an acuity chart, such as a ETDRS chart, including optotypes of a specific optotype luminance, such as Sloan letters, and a background such as an achromatic uniform color of a specific background luminance (white or grey). Other types of pictures adapted to test the vision of the individual may be used, as known by the man skilled in the art. The test picture may also comprise a duochrome test. The scene image is a virtual image formed by a projection optical system (and more precisely by the second projection sub-system) which projects a background picture displayed on a scene screen (or second screen), that optically transforms said scene picture into the virtual scene image. This background picture is preferably of an environment familiar to the individual, for example a natural environment, exterior or interior, such as a city, a landscape, a road or a room, and more preferably for mesopic conditions, a road at night seen through the windshield of an automobile (for example a part of a dashboard, steering wheel and of the rearview mirror of the automobile) surrounded by a landscape (trees, hills, clouds, city environment etc...).
The second screen is for instance one of the following: a LED or OLED screen, a serigraphy with backlight screen, a display light projection screen with micro video projector, an LCD screen or a TFT screen. It produces a light beam along a screen axis S perpendicular to the mean plane of the second screen. This light beam is meant to produce an image of a background picture (landscape, road, town... ).
The first and second projection sub-system allows the scene image to be superimposed with the visual test image and to be visible by the individual through the vision correction optical system, the scene image being observed at a background distance of projection from the individual’s eye 1 , whereas the test image being observed at the variable distance set. In practice, this background distance of projection is greater than or equal to the visual test distance of projection.
Such optometry system 10 is for example illustrated in documents EP3711654, EP3298952, EP3298951 , or EP4231892 and will not be described here in more details.
The visual target is displayed on said background. The luminance of the visual target, the luminance of the background of the screen, and the luminance of the casing may be controlled independently from one another and/or depending on specific light conditions to be used while performing the mesopic subjective refraction test.
The illustrated optometry system 10 and the optometry system involving a screen and a phoropter separated by a large distance (4-6 meters) in an examination room, comprise, according to the invention, an input device 60 for collecting information and answers of the individual, a computer to control the vision correction powers to apply to each eye, and the eyechart and background luminances depending on the progress of the subjective mesopic refraction determination method, as defined below. In particular, the input device 60 may comprise a joystick, a mouse, a keypad, or other input devices.
Said optometry system 10 also comprises a computer 50 with one or more processors programmed to: a) control the optometry device to determine a photopic value of said vision correction power of said corrective lens for each eye of said individual by achieving a photopic subjective refraction test in light conditions ensuring photopic vision of the eyes of the individual, or to retrieve an initial vision correction value stored in a memory of the optometry system, or to collect an initial vision correction value, b) validate a step of placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time, c) validate a step of placing the eyes of the individual in mesopic light conditions ensuring mesopic vision of the eyes of the individual and d) control the optometry device to achieve a mesopic subjective refraction test, said mesopic subjective refraction test comprising:
- fogging both eyes by providing to each eye a fogging test value of vision correction power equal to a predetermined fogging spherical power added to the corresponding photopic value of the vision correction power,
- iteratively adding to both eyes a same negative predetermined value of spherical power to said fogging test value and determining, each time said negative predetermined value of spherical power is added, a mesopic binocular visual acuity of the eyes until a maximum value of the mesopic binocular visual acuity is reached, thereby determining for each eye a mesopic raw value of the vision correction power equal to a test value of the vision correction power associated to the maximum value of the mesopic binocular visual acuity, e) determining, for each eye of the individual, said mesopic value of vision correction power based on said mesopic raw value of the vision correction power.
Said one or more processors are programmed to control the luminance of the screen 41 depending on the light conditions ensuring photopic, scotopic and mesopic vision in which the eyes of the individual are placed.
Said vision correction power may comprise a sphere value, and/or a cylinder value of an ophthalmic lens designed to correct the vision of the individual.
Step a)
In step a), the optometry device 20 is controlled by the computer 50 to determine a photopic value of said vision correction power of said corrective lens for each eye of said individual.
To this end, in a first embodiment a photopic subjective refraction test is achieved in light conditions ensuring photopic vision of the eyes of the individual. This photopic subjective refraction test corresponds to a conventional subjective refraction test and any known protocol for performing said subjective test may be used. Providing a luminance at the individual’s eyes level between 10 and 350 candela per square meter (cd/m2).
Preferentially, in step a) a maximum-plus maximum-visual acuity power (MPMVA power) is determined through the conventional photopic subjective test achieved. The maximum-plus maximum-visual acuity power corresponds to the most convex sphere value of the test values of the vision correction power provided to the eye of the individual allowing the best visual acuity of this eye.
Step a) aims to ensure the best focus under relaxed accommodation conditions of the eye before performing a subjective test in mesopic light conditions.
Step a) is performed under usual photopic light conditions. The usual photopic light conditions are obtained in a room with lights on, providing an illuminance at the individual’s eyes level between 10 and 350 lux, more preferably of about 45±5 lux.
Said one or more processors are programmed to control the luminance of the background of said optotypes to provide photopic light conditions. They may also control the light of the room where step a) is achieved.
The screen 41 of the display unit 40 is used to display a test picture comprising a visual target with a background luminance surrounding the visual target being comprised between 80 and 320 cd/m2, ideally around 200 cd/m2 and preferably of about 180 candela per meter square (cd/m2). The test picture is displayed with high contrast and high-luminance features.
In a first embodiment of step a), said optometry system comprises a device for determining an objective value of the vision correction power needed by each eye of the individual by aberrometry, automated refraction or retinoscopy.
The optometry system comprises for example an autorefractometer configured to determine, for each eye of said individual, a determined initial vision correction power value in photopic light conditions.
In another embodiment of step a), said optometry system comprises a memory storing for each eye a stored initial vision correction power value in photopic light conditions.
In another embodiment of step a), said input device 60 is used to collect, for each eye of the individual, a collected initial vision correction power value.
In each embodiment described above, said one or more processors are programmed to perform a preliminary step to set an initial photopic value of said vision correction power in photopic light conditions, as being equal to said determined and/or stored and/or collected initial vision correction power value for each of the eyes of the individual.
Said one or more processors are then programmed to start implementing said photopic subjective refraction test on the basis of said initial photopic value of said vision correction power for each eye of the individual.
The conventional photopic subjective test includes for example the following steps: i) monocular fogging of a first eye, ii) monocular defogging of said first eye, iii) monocular sphere searching aiming to determine the most convex sphere value of the test values provided to the eye of the individual allowing the best monocular visual acuity of this eye (monocular MPMVA), iv) monocular cylinder searching for said first eye, v) iteration of the previous step for the second eye, vi) bi-ocular balance or bi-ocular sphere adjustment determined for each eye while keeping both of the eyes of the individual open, vii) binocular balance or binocular sphere adjustment aiming to determine the most convex sphere value of the test values provided to both eyes of the individual allowing the best binocular visual acuity (binocular MPMVA); viii) measurement of photopic monocular and binocular visual acuity.
In the present description, the expression “bi-ocular" in “bi-ocular balance” will be used to indicate that the visual test performed allows testing one eye separately from the other, while keeping both eyes opened, thanks for example, to polarized lenses or prismatic lenses. In the present description, the expression binocular balance will be used to indicate that the visual test performed allows testing both eyes at the same time, while keeping both eyes opened. This is achieved by providing the same test image to the eyes.
The photopic subjective test is classically performed by presenting said visual test images to the individual and asking him to assess the quality of his perception of the visual targets of said visual test images and/or to identify optotypes characters. The individual is usually asked to compare his perception of two different visual test images or to identify characters of two different visual test images. The answers of the individual are provided to said computer 50 thanks to said input device 60.
Said one or more processors are programmed to set each next test value provided by said optical refraction element of the refraction test unit 30 according to the last answer collected by said input device 60 from the individual.
The step vii) of binocular balance may be performed from bi-ocular values determined in the step vi). The binocular balance step is generally handled as follows:
For example, a same binocular visual test image is provided to both eyes (block 100 of figure 2), then, a same positive predetermined spherical power value is added to said bi-ocular values determined in the step vi), to slightly fog both eyes, then a negative predetermined value of spherical power is iteratively added, until a maximum value of the photopic binocular visual acuity is reached.
More precisely, a same positive spherical power, for example equal to +0.25 diopters (D) is initially added to the current bi-ocular test value of each eye determined in step vi) (block 101 ) to slightly fog both eyes.
The one or more processors are then programmed to perform a visual acuity test (block 102).
If, further to the addition of the same positive spherical power, the visual acuity is identified as having decreased (arrow 104), said same positive spherical power is sufficient to slightly fog the individual’s vision and the binocular balance step can continue.
On the contrary, if, further to the addition of the same positive spherical power, the visual acuity is identified as not having decreased (arrow 103), meaning that said same positive spherical power is not sufficient to slightly fog the individual’s vision, the one or more processors are programmed to iteratively add additional predetermined fogging spherical power values until the visual acuity is identified as having decreased (arrow 104), the cumulative fogging spherical power values being at this stage sufficient to slightly fog the individual’s vision.
In these cases, the identification of a visual acuity decrease by the one or more processors can occur when the visual acuity is decreased by a minimal predetermined value, for example when an interface between an operator and the one or more processors is controlled by the operator to indicate such a decrease, for example when the operator observes that the individual cannot identify at least 3 characters out of 5 in a same line of an EDTRS visual chart.
Once the visual acuity decrease has been detected (arrow 104), the one or more processors are programmed to iteratively add a negative predetermined value of spherical power, until a maximum value of the photopic binocular visual acuity is reached.
More precisely, a first negative predetermined value of spherical power is added (block 105) corresponding in absolute value to the last added fogging spherical power value. For example, if the last added additional predetermined value of fogging spherical power equals +0.25 diopters (D), this value is removed from the current test value of each eye (block 105).
The one or more processors are then programmed to perform a visual acuity test (block 106).
If, further to the addition of the first negative predetermined value of spherical power, the visual acuity is identified as having improved (arrow 107), then said one or more processors are programmed to iteratively continue to add a negative predetermined value of spherical power to the current test value and to determine, each time said negative predetermined value of spherical power is added, a photopic binocular visual acuity of the eyes, until a maximum value of the binocular visual acuity is reached.
If, further to the addition of a first negative predeterm ined value of spherical power, the visual acuity is identified as not having improved (arrow 108), a maximum value of the binocular visual acuity has been reached.
In these cases, the identification of the maximum value of the binocular visual acuity occurs when, further to the addition of a negative predetermined value of spherical power, the visual acuity that was previously recording as improving decreases or does not improve with the last added value of the negative predetermined value of spherical power. The last added value of the negative predetermined value of spherical power is removed (block 109) and the obtained test value is considered as the photopic binocular visual acuity of the eyes for which a maximum value of the binocular visual acuity is reached.
More precisely, these sub-steps are repeated until the visual acuity test indicates that the visual acuity does not improve anymore. An example of visual acuity improvement can be characterized by the identification by the individual of 3 out of 5 characters of a line in a ETDRS chart
Once the fact that the visual acuity does not improve anymore has been recorded (arrow 108), the one or more processors are programmed to undo the addition of the last increment of negative spherical power. For example, a positive sphere power equal to the opposite of the last negative increment of sphere power is added, for example +0.25 diopters (D) is added to the current test value of each eye (block 109).
The final current test value then corresponds to the most convex sphere values allowing the best visual acuity in photopic light conditions. The photopic subjective refraction test is ended (block 110).
The photopic subjective refraction test provides, for each eye of the individual, the most convex sphere values allowing the best visual acuity in photopic light conditions corresponding to the binocular photopic MPMVA power (Maximum Plus Maximum Visual Acuity power). These values are used preferably to determine monocular and binocular visual acuities, and to start the mesopic subjective refraction test, as described hereafter.
Step b)
The one or more processors of the computer 50 are programmed to request the achievement of a step of placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time.
The individual or the user of the optometry system 10 is then required to perform an action indicating that this step has been achieved through the input device 60 of the system. This action may comprise checking or clicking a validate button. In practice, said one or more processors requests that the individual is subjected to a short-time adaptation to the dark. The individual is placed in scotopic vision conditions providing a luminance at the individual’s eyes level of less than 0.005 cd/m2 Said predetermined amount of time is comprised between 2 minutes and 10 minutes, more preferably between 2 minutes and 5 minutes, more preferably equals to 2.5 minutes. It is preferentially over 2 minutes, preferentially equal to 2.5 minutes or more.
Adapting the eyes of the individual to scotopic vision light conditions avoids mesopic visual acuity fluctuation due to progressive changes in the eyes sensitivity after passing directly from photopic to mesopic light conditions.
The usual scotopic vision light conditions are obtained in dark room with no artificial nor natural light.
The optometry system 10 may comprise additional accessories to obtain said scotopic vision light conditions, such as occluders or dark cover for the optometry device, sunglasses or opaque mask for the eyes of the individual.
The step of placing the individual in said scotopic vision light conditions may in particular be performed by:
- using covering sunglasses of category 4 or 3 like fit-over sunglasses in a dark room ;
- using neutral density filters of transmittance of 10% or lower on trial lenses in dark room;
- setting-up occluders on a phoropter or refractor head in a dark room and placing the individual as close as possible to the refractor head or phoropter;
- using immersive mask as for instance a virtual reality face mask;
- using a fabric cloth on the phoropter or refractor head;
- positioning neutral density filters of transmittance of 10% or lower in the phoropter along the optical path;
- using a “night mode” for the keyboard and displaying interface controlling the optometry device at the disposition of the expert testing the subject, in which the keyboard/mouse/ displaying interface would have no back lighting, and the digital interface would have a dark background and slightly bright letters as the one of a GPS device set in night mode ;
- any combination of all the previous options leading to the scotopic level of luminance. In all cases, the individual should have his eyes opened during step b).
Said one or more processors may be programmed to control the lights of the room and/or the lights of the optometry device when step b) is carried out.
Moreover, the one or more processors of the computer 50 can be programmed to broadcast pre-registered audio information on the next steps of the test, pre-registered questions to the subject relative to his/her discomfort/difficulties encountered specifically at night, for example when driving, and/or collect oral and/or visual input responses/reactions/behaviours of the subject during the step of placing the individual in said scotopic vision light conditions.
Step c)
After step b) aiming to adapt the eyes of the individual to darkness, said one or more processors of the computer 50 are programmed to request the achievement of a step of placing the eyes of the individual in light conditions ensuring mesopic vision of the eye of the individual.
The individual or the user of the optometry system 10 is then required to perform an action indicating that this step has been achieved through the input device 60 of the system. This action may comprise checking or clicking a validate button.
In practice, the individual is placed in mesopic light conditions providing a luminance at the individual’s eyes level between 0.005 and 5 cd/m2 more preferably about 1 cd/m2. This is obtained in a dark room with a minimum of artificial or natural light allowing said mesopic light conditions, and preferably with no artificial or natural light. Other parasite light sources should also preferably be avoided.
Said one or more processors may be programmed to control the lights of the room where step c) is carried out.
Step d)
Said one or more processors are programmed to control the optometry device 20 to achieve a mesopic subjective refraction test.
During step d), the light conditions of the room are mesopic light conditions, provided preferably with a dark room or with a minimum of artificial or natural light. Said one or more processors are programmed to control the luminance of the background of said acuity chart to provide mesopic light conditions and the luminance of the optotypes of the acuity chart themselves to provide scotopic or mesopic conditions. More precisely, under said mesopic light conditions, the screen 41 of the optometry system 20 is controlled by said one or more processors to display visual acuity optotypes such as Sloan letters, numbers, Snellen’s E or Landolt’s C or drawings with mesopic luminance between 0.005 and 5 cd/m2 (for example 0.04 cd/m2) or with scotopic luminance below 0.005 cd/m2, and the background of said optotypes with mesopic luminance comprised between 0.005 and 5 cd/m2, for example equal to about 1 cd/m2. An adjustment of the binocular sphere only is conducted by searching the MPMVA power according to the steps described hereafter.
Said one or more processors are programmed to control the luminance of the screen depending on the light conditions ensuring photopic, scotopic and mesopic vision in which the eyes of the individual are placed.
The luminance level of the room of a non-compact optometry system and/or of the casing of a compact optometry system, may differ from the luminance level of the screen (visual tests) for a same light environment condition (photopic, mesopic, scotopic). For example, for mesopic conditions, luminances of the chart background, of the room and/or of the casing of the non-compact optometry system should all be in the mesopic levels, and the luminance level of the chart background should preferably be higher than the luminance level of the room and/or of the casing of the compact optometry system, for example higher by at least as 5 percent.
As a starting point of the mesopic subjective refraction test, the eyes of the individual are provided with the photopic values of the vision correction power determined in step a).
These values correspond here to the most convex sphere values allowing the best visual acuity in photopic light conditions for each of the eyes of the individual.
In a preliminary optional first sub-step of the mesopic subjective refraction test, the one or more processors are programmed to determine the binocular visual acuity of the eyes with each eye provided with said photopic value of the vision correction power determined in step a), while the eyes are placed in mesopic light conditions (block 200 of figure 3). This step may also be performed during step e) instead, as mentioned below.
This first sub-step provides information on the shift in visual acuity induced by the change in lighting environment. With the visual acuity value obtained in this first sub-step, it is possible to compare the visual acuity obtained with the photopic value of the vision correction power determined in step a) in photopic light conditions and the visual acuity obtained with the photopic value of the vision correction power in mesopic light conditions of the current first sub-step.
In a first step of the mesopic subjective refraction test, the one or more processors are programmed to provide to each eye a fogging test value of vision correction power equal to a predetermined fogging spherical power added to the corresponding photopic value of the vision correction power, in order to fog both eyes, the individual still being exposed to mesopic light conditions.
For example, a positive sphere power, for example equal to +0.5 diopters (D) is added to the current test value of each eye (block 201 ).
The one or more processors are then optionally programmed to perform a visual acuity test which should confirm that further to the addition of the same positive spherical power, the visual acuity is identified as having decreased.
In a second step of the mesopic subjective test, the one or more processors are programmed to add to both eyes at the same time a same increment of negative sphere power to said fogging test value.
For example, a negative sphere power, for example equal to -0.25 diopters (D) is added to the current test value of each eye (block 202).
In a third step, the one or more processors are programmed to perform a binocular visual acuity test (block 203), and iteratively add to both eyes a same increment of negative sphere power value as long as the visual acuity test indicates that the visual acuity is improved by said addition of an increment (arrow 204). For example, said negative increment of sphere power, for example equal to -0.25 diopters (D) is iteratively added to the current test value of each eye (arrow 204) for both eyes at the same time.
In order to reduce variability, the one or more processors are programmed to perform a double check of visual acuity with two different acuity charts of optotypes.
Preferably, these sub-steps are repeated as long as the improvement of the visual acuity is over a predetermined threshold.
For example, the addition of the negative increment is repeated as long as the subsequent binocular visual acuity test shows a gain of 1 letter or more, preferably of at least 2 letters out of 5 letters of the binocular visual acuity line and up to the maximum visual acuity is reached, that means until the visual acuity test indicates that the visual acuity does not improve anymore (arrow 205 of figure 2).
Once the fact that the visual acuity does not improve anymore has been recorded (arrow 205), the one or more processors are programmed to undo the addition of the last increment of negative sphere power. For example, a positive sphere power equal to the opposite of the negative increment of sphere power is added, for example +0.25 diopters (D) is added to the current test value of each eye (block 206).
Therefore, each time said increment of negative sphere power is added, the one or more processors are programmed to determine a current value of binocular visual acuity of the eyes in said mesopic light conditions, until a maximum value of the mesopic binocular visual acuity is reached, corresponding to the binocular mesopic MPMVA power (Maximum Plus Maximum Visual Acuity power).
Thus, the test value used in the step before the last step that does not lead to a visual acuity improvement is kept and constitutes the final current test value.
The final current test value then corresponds to the most convex sphere values allowing the best binocular visual acuity, that is to say the MPMVA, in mesopic light conditions. The mesopic subjective refraction test is ended (block 206).
The one or more processors are then programmed to determine a mesopic raw value of the vision correction power for each eye of the individual, said mesopic raw value of the vision correction power being equal to the test value of the vision correction power associated to the maximum value of the mesopic binocular visual acuity.
At this stage, the one or more processors may be programmed to perform, in mesopic light conditions, a binocular mesopic visual acuity test with the mesopic raw value of the vision correction power just determined and compare it with the binocular mesopic visual acuity test implemented at the beginning of the present step d) determined in step a), with the photopic value of the vision correction power determined in step a). The difference is calculated by the processors and shows the improvement of acuity due to the mesopic raw value of the vision correction power.
The MPMVA power is here the mesopic raw value of the vision correction.
The individual may also visualize the difference between the vision correction provided by the photopic and mesopic values of vision correction power. The one or more processors are programmed to display on the screen an image in mesopic light conditions and to control the optical units so as to provide the individual : first with the vision correction power determined in photopic conditions in step d) and second with the mesopic raw value of the vision correction power determined in mesopic conditions. An example of the image displayed in mesopic light conditions is shown on figure 5.
The difference existing between the mesopic raw value of the vision correction power corresponding to the binocular mesopic MPMVA power determined in the present step d) of the mesopic subjective refraction test, and the vision correction power corresponding to the binocular photopic MPMVA power determined in the step a), constitutes a raw refraction shift.
Step e)
Said mesopic value of said vision correction power is determined by said one or more processors based on said mesopic raw value of the vision correction power
In a first simplified embodiment of step e), said one or more processors are programmed to determine a refined mesopic value of said vision correction power based on said mesopic raw value of the vision correction power.
For example, said refined mesopic value of said vision correction power is set as equal to said mesopic raw value of the vision correction power.
The refined mesopic value of said vision correction power then constitutes the mesopic value of the vision correction power looked for.
In a second preferred embodiment of step e), the one or more processors may be programmed to perform, after the mesopic subjective refraction test described above, a mesopic visual appreciation test with the following steps, shown schematically on figure 4:
- controlling (block 300 of figure 4) the optometry device for providing each eye of the individual with the mesopic raw value of the vision correction power determined in step c),
- for each eye, controlling the optometry device for adding a predetermined negative value of spherical power to said mesopic raw value of the vision correction power (block 301 of figure 4) and
- collecting (block 302) an answer of the individual asked to compare his visual performance with and without the added predetermined negative value of spherical power,
- based on this comparison, determining said refined mesopic value of vision correction power for each eye of the individual by adding a refining value of spherical power to said mesopic raw value of the vision correction power for each eye, aiming at improving the quality of mesopic vision and depending on said predetermined negative value of spherical power (blocks 310, 311 , 312, 313 of figure 4).
The refining value of spherical power added by said one or more processors comprises one of the following:
- said predetermined negative value of spherical power,
- a positive or negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power,
- a null value.
In practice, this mesopic appreciation test is conducted in mesopic light conditions, by comparing the visual quality of the individual looking at the mesopic visual test image with high contrast and low luminance, for example 1 cd/m2 with and without a binocular addition of -0.25D to the mesopic raw value of the vision correction power.
Said one or more processors are programmed to request and collect the answer of the individual (block 302).
This answer may be among the following:
- Better visual quality with added predetermined negative value of spherical power (arrow 302A of figure 4),
- Better visual quality without added predetermined negative value of spherical power (arrow 302B of figure 4),
- No difference between vision with and without added predetermined negative value of spherical power (arrow 302C of figure 4).
According to the collected answers, the one or more processors are programmed to perform actions according to a decision tree. An example of such a decision tree is shown on figure 4. When said comparison shows a difference in the visual performance of the eyes of the individual, either in favor of the vision with said added predetermined negative value of spherical power (arrow 302A) or in favor of the vision without said added predetermined negative value of spherical power (arrow 302B), said one or more processors are additionally programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important (blocks 303 and 304 of figure 4). In other words, the one or more processors are programmed to request and collect the answer of the individual asked to qualify the difference of visual performance with and without said added predetermined negative value of spherical power among the following possibilities: slight, moderate or important (blocks 303 and 304).
When said answer indicates an important difference in the visual performance of the eyes of the individual in favor of his visual performance without the added predetermined negative value of spherical power (arrow 303A), said one or more processors are programmed to add the refining value of spherical power equal to said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power (block 305).
Said one or more processors are programmed to determine said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power as being equal to a fraction of the absolute value of said predetermined negative value of spherical power.
For example, here the said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power is equal to half of the absolute value of the predetermined negative value of spherical power. It is then equal to +0.125 D.
Said one or more processors are then programmed to determine said refined mesopic value of vision correction power for each eye of the individual as equal to said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power added to said mesopic raw value of the vision correction power determined in step d) for each eye (block 310 of figure 4).
When said answer indicates a slight or moderate difference in the visual performance of the eyes of the individual in favor of his visual performance without the added predetermined negative value of spherical power (arrow 303B), said one or more processors are programmed to add the refining value of spherical power equal to said null value (block 306 of figure 4).
Said one or more processors are then programmed to determine said refined mesopic value of vision correction power for each eye of the individual as equal to said mesopic raw value of the vision correction power determined in step d) for each eye (block 311 of figure 4).
When said answer indicates a slight or moderate difference in the visual performance of the eyes of the individual in favor of his visual performance with the added predetermined negative value of spherical power (arrow 304A) or when said comparison of the visual performance of the individual with and without the added predetermined negative value of spherical power shows no difference in the visual performance of the eyes of the individual (arrow 302C), said one or more processors are programmed to add the refining value of spherical power equal to said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power (block 307).
Said one or more processors are programmed to determine said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power as being equal to a fraction of the predetermined negative value of spherical power.
For example, here said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power is equal to half of the predetermined negative value of spherical power. It is then equal to -0.125 D.
Said one or more processors are then programmed to determine said refined mesopic value of vision correction power for each eye of the individual as equal to said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power added to said mesopic raw value of the vision correction power determined in step d) for each eye (block 312 of figure 4).
If there is no difference or a “slight” to “moderate” difference in favor of the vision with the mesopic raw value of the vision correction power with added predetermined negative value, focus giving best vision quality is indeed between the mesopic raw value and the mesopic raw value with added predetermined negative value.
When said answer indicates an important difference in the visual performance of the eyes of the individual in favor of his visual performance with the added predetermined negative value of spherical power (arrow 304B), said one or more processors are programmed to add the refining value of spherical power equal to said predetermined negative value of spherical power (block 308).
In the example described here, -0.25 D is added.
Said one or more processors are then programmed to determine said refined mesopic value of vision correction power for each eye of the individual as equal to said predetermined negative value of spherical power added to said mesopic raw value of the vision correction power determined in step d) for each eye (block 313 of figure 4).
Said optometry system may moreover comprise a communication device for sending said refined mesopic value of the vision correction power to a manufacturing unit for ophthalmic lenses providing said mesopic value of the vision correction power to be manufactured.
Alternatively, said optometry system is part of a manufacturing system comprising a manufacturing line comprising a manufacturing device for manufacturing ophthalmic lenses and said manufacturing device is controlled by said one or more processors to manufacture an ophthalmic lens providing a refraction power equal to said refined mesopic value of the vision correction power.
Finally, in an additional step, the one or more processors may be programmed to successively provide the individual with the refined mesopic value of the vision correction power determined in step e) and the photopic value of vision correction power determined in step a), in mesopic light conditions, in order for the individual to be able to compare and visualize the gain in visual performances (acuity, comfort, clarity of vision... ) provided by the refined mesopic value of the vision correction power in mesopic light conditions compared to the visual performances obtained in the same mesopic light conditions but with a photopic value of vision correction power.
Optionally, if the above mentioned preliminary optional first sub-step of the mesopic subjective refraction test was not performed i.e. if no binocular visual acuity of the eyes, each eye being provided with the corresponding photopic value of the vision correction power determined in step a) was not performed at the beginning of the step e), said one or more processors are programmed to determine, in an optional final sub-step e), a binocular visual acuity of the eyes, each eye being provided with the corresponding photopic value of the vision correction power determined in step a). Implementing such a binocular visual acuity of the eyes, each eye being provided with the corresponding photopic value of the vision correction power determined in step a), just after having provided each eye with the mesopic value of the vision correction power determined in the current step e), allows to ensure that both visual acuities are determined after almost a same dark adaptation time in mesopic light conditions and therefore allows a better comparison one another.
The individual may also visualize the difference. The one or more processors may be programmed to display on the screen an image in mesopic light conditions with a line of Sloan letters of typical EDTRS chart or other typical acuity optotypes with an achromatic grey background of mesopic luminance, an example of which is shown on figure 5, and to control the optical units so as to provide the individual firstly with the photopic value of vision correction power determined in photopic conditions in step d), and, secondly, with the refined mesopic value of the vision correction power determined in mesopic conditions.
The difference existing between the refined mesopic value of the vision correction power determined in the present step e) of the mesopic subjective refraction test, and the vision correction power corresponding to the binocular photopic MPMVA power determined in step a), constitutes a refined mesopic refraction shift.
The refined mesopic refraction shift may be determined under different light environments, for example in two mesopic light environments simulating respectively bad-lit roads and moderate-lit roads at night.
More precisely, night driving light environment is dynamic, covering a wide luminance range. According to Ell norms (Ell EN-13201 ), road lighting at night can be classified in six levels from well-lit roads (luminance average 2 cd/m2) as urban roads or highways with high traffic, and bad-lit roads (luminance average 0.3 cd/m2) as secondary roads or highways with low traffic. Thus, the refined mesopic refraction shift produced from photopic conditions and the associated change in visual acuity might be different according to change in night road lighting where people are driving. This is the reason why the refined mesopic refraction shift will preferably be measured under two mesopic luminance levels (medium and low mesopic optotype’s luminance level).
Thus, two different background luminances of the visual optotypes can be used to assess refined mesopic refraction shift and visual acuity shift produced from photopic to mesopic simulated night-driving light conditions: a first moderate mesopic luminance value to simulate a moderate-mesopic level (1 cd/m2 for example) simulating moderate-lit roads at night, and a second low mesopic luminance to simulate a low-mesopic level simulating low-lit roads at night (0.36 cd/m2 for example).
Either one of the moderate or the low level mesopic luminance tests could be used for refined mesopic refraction shift assessment even though there is an individual variability in obtained results. Figure 6 represents the differences in refined mesopic refraction shift obtained with mesopic refraction tests performed with moderate (1.1 cd/m2) and low (0.36 cd/m2) level mesopic luminance respectively:
For the moderate mesopic luminance test achieved with background luminance of 1.1 cd/m2:
- the median value is -0.37 diopter (D) with an interquartile range of 0.25D,
- the mean value is -0.45 D with a standard deviation of -0.16 D,
- the range is -0.87 to 0.25 D.
For the low mesopic luminance test achieved with background luminance of 0.36 cd/m2:
- the median value is -0.62 diopter (D) with an interquartile range of 0.25D,
- the mean value is -0.53 D with a standard deviation of -0.22 D,
- the range is -0.87 to 0.125 D.
The calculated significance or “p-value” (as defined in https://en.wikipedia.org/wiki/P-value) of p=0.07, shows that the difference between the results obtained with the two different mesopic levels of luminance is not significant. In other words, the results obtained with the two mesopic levels of luminance are equivalent since said p-value is superior to 0.05.
Thus, a single mesopic luminance test might be used for measuring the refined mesopic refraction shift. If only one mesopic level was to be chosen to assess the refined mesopic refraction shift compared to photopic value, the preferred mesopic level would be the moderate-mesopic level (for example 1 cd/m2) as the visual acuity dispersion is lower for a test with a luminance of moderate mesopic level than for a test with a luminance of low mesopic level.
The preferred mesopic luminance level to assess the refined mesopic refraction shift is the moderate mesopic level.
In an embodiment, a single mesopic refraction test is performed with a mesopic luminance to measure said refined mesopic refraction shift.
Figure 7 shows a Bland-Altman’s plots of agreement in refined mesopic refraction shift between the results of two mesopic refraction tests performed with two different background luminances : a moderate mesopic luminance of 1.1 cd/m2 and a low mesopic luminance of 0,36cd/m2.
On this figure 7, the line noted “Bias” is the average difference between the refined mesopic refraction shifts measured with the two test background luminances. The 95% limits of agreement “LoA” corresponds to almost 2 standard deviation (SD) from the average difference, more precisely equal to 1.96 SD, from the average difference between the refined mesopic refraction shifts measured with the two test background luminances.
Bland-Altman plots are extensively used to evaluate the agreement among two different instruments or two measurements techniques. Bland-Altman plots allow identification of any systematic difference between the measurements (i.e., fixed bias) or possible outliers. The 95% limits of agreement for each comparison (average difference ± 1.96 standard deviation of the difference), give indications about how far apart the shifts measured by the two tests were more likely to be for most test subjects.
According to the Bland-Altman’s agreement plot of figure 7, the mean difference between the refined mesopic refraction shifts measured with the two test background luminances is close to zero, exactly -0.07 D and 95% limits of agreement is ±0.46D; Thus, 95% of the differences in shifts between the two tests performed with different luminances fall within +0.39D and -0.53D.
The visual acuity of the individual provided with a same vision correction power may vary when the light conditions vary from photopic to mesopic light conditions. Figure 8 shows the visual acuity shift measured with different light conditions and different values of spherical power of a test lens placed in front of the eye of the individual.
The two results represented on the left side of the graph correspond to the visual acuity shifts measured with moderate mesopic luminance of the test background equal to 1 .1 cd/m2 and low mesopic luminance of the test background equal to 0,36cd/m2 while the individual is provided with a test lens having optical features corresponding to the photopic value of vision correction of the individual (marked as “w/photopic Rx”). This represents the (physiological) visual acuity loss in mesopic conditions due to change of light environment. The visual acuity of the individual decreases additionally by one line with the lower test luminance compared to the moderate test luminance.
The two results represented on the right side of the figure correspond to the visual acuity shifts performed with moderate mesopic luminance of the background equal to 1 .1 cd/m2 and low mesopic luminance of the background equal to 0,36cd/m2 while the individual is provided with a test lens having optical features corresponding to the mesopic value of vision correction power of the individual. The refined mesopic refraction shift is compensated. The visual acuity of the individual additionally increases by 0.05 logMAR units (half of a VA line) is higher with the lower test luminance compared to the moderate test luminance. Higher dispersion of visual acuity is observed with the lower test luminance.
Even though a single test luminance is recommended, the use of two mesopic luminances in the assessment of the refined mesopic refraction shift might be used to subjectively test visual acuity loss occurring with the photopic value of vision correction power and visual acuity gain produced with the mesopic value of the vision correction power determined in low mesopic light conditions and moderate mesopic light conditions.
Moreover, the displaying interface at the disposition of the expert testing the subject with the optometry device according to the invention, could be controlled so as to disclose in addition to the information and datas relative to the refraction determination, and/or relative to the patient, a reproduction of the test image currently displayed for the subject, and for compact optometry device, a reproduction of the scene image if present, so as to ensure the display of the proper image luminance for the current lighting condition of the pending step of the protocol. According to the invention, said one or more processors may additionally be programmed to perform a step of evaluation of the visual performances of the individual while his eyes are placed in light conditions ensuring mesopic vision and provided either with the photopic value of the vision correction power determined in step a) or with the mesopic value of the vision correction power determined in step e).
Moreover, still in light conditions ensuring mesopic vision said one or more processors may be programmed to further perform a step of evaluation of the visual performances on mesopic contrast sensitivity when provided either with the photopic value of the vision correction power determined in step a) or with the mesopic value of the vision correction power determined in step e).
More specifically, during this step, the test image may show optotypes on a background with a lower contrast than the contrast of the test image shown during the mesopic value determination of step e), for example at low or very low contrast conditions.
For example, the device can be programmed to implement a contrast sensitivity test. Accordingly, as disclosed in the Figure 16, this test can involve a mesopic contrast sensitivity test image comprising:
• a background with mesopic luminance (for example between 0.005 to 5 cd/m2) and more preferably 1 cd/m2,
• optotypes with a same angular size (same height) organized by lines, each line having optotypes of a same mesopic luminance, lower than the mesopic luminance background, the different lines of optotypes having decreasing optotypes mesopic luminances from the upper line, to the lower line, in order to achieve a contrast optotype/background between 100% and 10%, the contrast optotype/background value C being calculated by the Weber formula = (Lb-Lt)ZLb where Lb is the mesopic luminance background and the Lt is the mesopic luminance of the optotype.
The contrast value is determined as being the lowest one at which the subject is able to read for example 3 optotypes out of 5.
The contrast sensitivity is the reciprocal of the contrast value (CS=1/C). It can be calculated respectively when the mesopic correction value and when the photopic correction value, are provided to the subject, and compared one another to demonstrate the benefit for the subject of the mesopic correction.
According to another embodiment, the device can be programmed to implement a contrast acuity test. Accordingly, as disclosed in the Figures 17 and 18, this test can involve a mesopic contrast acuity test image comprising:
• a mesopic luminance background (0.005 to 5 cd/m2) and most preferable 1 cd/m2,
• optotypes organized by lines of decreasing angular size (height or acuity) from the upper line to the lower line, like an ETDRS test or Landolt’s C test, the optotypes of the different lines having a same mesopic luminance, being lower than the mesopic luminance background.
Several mesopic contrast acuity test images having same mesopic background luminance and different mesopic optotypes luminance, in order to achieve optotype/background contrasts between 100% and 10%, more preferably of 40%.
Contrast optotypes/background is calculated by the Weber formula = (Lb- Lt)/I_b where Lb is the mesopic luminance background and the Lt is the mesopic luminance of the optotype. For instance, for 40% weber’s contrast chart: Lb=1.12cd/m2, Lt=0.655 cd/m2 Cw=0.42.
These mesopic contrast tests could also be integrated on a night simulated scene.
Moreover, still in light conditions ensuring mesopic vision, said one or more processors may be programmed to further perform a step of evaluation of the visual performances on glare sensitivity when provided either with the photopic value of the vision correction power determined in step a) or with the mesopic value of the vision correction power determined in step e).
More specifically, during this step, the screen showing the test image is equipped with light sources and the one or more processors may be programmed to turn on said light sources so as to simulate a glare situation, while providing the subject either with the photopic value of the vision correction power determined in step a) or with the mesopic value of the vision correction power determined in step e).
More specifically, the optometry device according to the invention can disclose in the pictures displayed by the screen and/or provide directly or indirectly, additional lighting spots imitating the kind of disturbing lights encountered at night (moon light, street lights, headlights of cars traveling in the opposite direction and/or reflecting in the side or inner rear mirror of a car... ) so as to test the level of discomfort of the subject or the performance reached by the specific correction brought by the refraction unit.
In a not illustrated embodiment, such light source(s) can be brought by a specific light source such as a LED, or LED strip(s).
This light source may be:
- fixed on the edge(s) of the screen placed at 5-6 meters from the subject for non-compact optometry systems, and at a location matching with a background image defined for the purpose of testing blur sensitivity of the subject (for example, an isolated LED fixed on the lateral edge of the screen appearing as a street lamp of a street image displayed by the screen),
- or, for compact optometry device: o fixed inside the casing, o fixed on an inner wall of the casing on the optical path seen by the observer directly or further to a reflection on a mirror or beam splitter, o fixed on the scene screen’s edge (for example on the scene screen’s edge(s), i.e. around the background picture displayed by the scene screen), and/or o fixed on the test screen ’s edge (for example on the test screen’s edge(s), i.e. around the test image displayed by the test screen, the light source being integrated in the image observed by the subject when the scene image and the test image provided by the test screen are superimposed.
This light source may be fixed so as to define moving light(s) such as lights of a moving car, for example, the light source can comprise LEDs strips that could be fixed on the test screen edges and each LED could be individually controlled so as to define when the test image is superimposed with a scene image defined accordingly, a dynamic and apparently moving lighting simulating for example lights of a car moving toward the subject in a highway background. Alternatively, or in addition, a fixed and powerful LED could be fixed on the test screen’s edge so as to define when the test image is superimposed with a scene image defined accordingly, a powerful lighting such as a street lamp or a dazzling lighting appearing in the inner or lateral mirror of a car.
More specifically, the device can be programmed to implement a glare sensitivity test to measure subjectively the benefit of the mesopic vision correction (step e) on discomfort on a glare simulated situation, compared to photopic vision correction.
This test can be implemented:
• after sensitivity contrast benefit evaluation, or
• after step e) mesopic vision correction value determination.
The subject can look at a night simulated scene (may integrate mesopic visual acuity test pannel or contrast acuity pannel).
The types of glare can involve: fixed light sources on the edge of screens (one, two or all sides) simulating streetlights or car’s headlights from the left or right side on the road, dynamic glare sequence simulating dynamic glare from car’s headlights, a single LED or several LEDs,
LED’s spectrum might variate to measure different sensibility (Cold white LED, warm white LED, red LEDS... ) and/or have a temporality: intermittent LED’s simulating bycicles LEDs.
The overall protocol sequence can involve:
• photopic vision correction value,
• scotopic period,
• mesopic vision correction value,
• mesopic visual acuity determination with mesopic correction and with photopic correction to show the benefit of mesopic correction on visual acuity,
• mesopic contrast visual performance evaluation (contrast acuity or contrast sensitivity) to show the benefit of mesopic correction on contrast vision,
• glare assessment in mesopic conditions to show the benefit of mesopic correction on glare discomfort.
The visual performances of the individual are assessed either thanks to a comparison of the individual’s feedbacks or of the binocular visual acuities determined respectively between the vision correction power determined in step a) or with the mesopic vision correction power determined in the step e). This assessment allows to receive the individual’s subjective feedback in mesopic light conditions about the benefit of the mesopic vision correction over the photopic vision correction in mesopic light conditions.
The optometry system of the invention described above allows implementing the method of the invention for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions, using an optometry device having a refraction test unit with two optical refraction elements, each optical refraction element being adapted to provide test values of said vision correction power to one of the eyes of the individual, said method comprising the following steps: a) determining a photopic value of said vision correction power of said corrective lens for each eye of said individual by achieving a photopic subjective refraction test in light conditions ensuring photopic vision of the eyes of the individual, b) placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time, c) placing the eyes of the individual in light conditions ensuring mesopic vision of the eyes of the individual and d) achieving a mesopic subjective refraction test, said mesopic subjective refraction test comprising:
- fogging both eyes by providing to each eye a fogging test value of vision correction power equal to a predetermined fogging spherical power added to the corresponding photopic value of the vision correction power,
- iteratively adding to both eyes a negative predetermined value spherical power to said fogging test value and determining, each time said negative predetermined value of spherical power is added, a mesopic binocular visual acuity of the eyes until a maximum value of the mesopic binocular visual acuity is reached, thereby determining for each eye a mesopic raw value of the vision correction power equal to a test value of the vision correction power associated to the maximum value of the mesopic binocular visual acuity, e) determining, for each eye of the individual, said mesopic value of said vision correction power based on said mesopic raw value of the vision correction power.
A method for manufacturing an ophthalmic lens adapted to correct the vision of a individual may comprise the step of implementing said method for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions according to the invention and a step of manufacturing said ophthalmic lens such that it presents said mesopic value of the vision correction power.
The optometry system and method of the invention provides a mesopic value of vision correction power for the eyes of the individual, based on a subjective test performed in mesopic light conditions comprising exclusively binocular steps. This provides a quick and reliable mesopic value of vision correction power.
The mesopic appreciation test optionally performed in step e) provides a better accuracy by refining mesopic vision correction in 0.125D steps leading to visual performance improvement.
The invention allows taking into account and correcting the loss of visual acuity due to decrease in luminance (from photopic to mesopic) and the shift of subjective refraction in 0.125D steps, resulting in a gain of visual acuity, contrast sensitivity and quality of vision with the refined mesopic value of the vision correction power. It is especially useful to provide the individual with a vision correction equipment comprising ophthalmic lenses with said refined mesopic value of the vision correction power for night driving conditions.
The benefit of using an ophthalmic lens exhibiting said refined mesopic value of the vision correction power on visual acuity in mesopic light conditions was shown in a clinical study by the Applicants.
In this study, 115 healthy subjects who usually drive 4 days a week with at least 20 min each day of nighttime driving were recruited with 61 women and 54 men, comprising 82 non-presbyopes drivers and 33 presbyopes drivers.
In an initial test, the method of the invention was applied with the optometry system of the invention, with a predetermined amount of time of 5 minutes in step b) by using a precise refraction in photopic light conditions by means of a phoropter based on continuously variable power which allow power steps of 0.01 D. The amount of time defined in step b) is called in the following the “dark adaptation time”.
The screen displayed optotype with a background having a background luminance of 1.1 cd/m2 during step d).
A significant average visual acuity loss of 2 lines of EDTRS chart was recorded when light conditions were changed from photopic to mesopic light conditions while the subjects wore ophthalmic lenses with photopic value of the vision correction power, as shown on figure 9. A significant average visual acuity improvement of 1 line of EDTRS optotypes was recorded in mesopic light conditions when the subject switched to ophthalmic lenses having said mesopic value of the vision correction power determined with the optometry system and method according to the invention.
More precisely, figure 10 shows values of mesopic visual acuity shifts (VA Shift) measured when changing the light conditions from photopic to mesopic light conditions, while the individual is provided with the photopic value of vision correction power (w/STD Rx) on the left side of figure 10, and measured when changing the value of vision correction power from photopic to mesopic value of vision correction power while the individual is placed in mesopic light conditions (w/NIGHT Rx), on the right side of figure 10.
With standard photopic value of vision correction power, the logMAR visual acuity shift measured when changing the light conditions from photopic to mesopic light conditions is 0.19, implying a loss of two lines of visual acuity, whereas, with mesopic light conditions, the logMAR visual acuity shift is -0.06 when changing the value of vision correction power from photopic to mesopic value of vision correction power, implying a gain of one line of visual acuity.
Statistically, there is strong evidence that the compensation of the myopic refraction shift by the refined mesopic correction is associated to the gain of visual acuity. Indeed, there is less than 5% of probability that the gain in visual acuity is due to chance since the p-value (or probability value) is below 0.05.
It was moreover shown that subjects exhibiting either a higher shift in measured refraction or a higher loss in visual acuity when light conditions were changed from photopic to mesopic light conditions also exhibited a higher visual acuity gain when provided with ophthalmic lenses having said mesopic value of the vision correction power.
In said above-described initial test of the clinical study, 96 subjects out of 115 (83%) did exhibit a myopic refraction shift, in other words a significant difference between the values of the vision correction power determined in photopic conditions and in mesopic conditions according to the present invention, for example for subjects with a myopic refraction shift over 0.25 D. For these subjects, when facing a mesopic image in mesopic light conditions:
91 % (n=87) preferred the refined mesopic value of vision correction power, 5% (n=5) the photopic value of vision correction power, 4% (n=4) had no preference.
In said initial test of the clinical study, 19 subjects out of 115 (17%) did not exhibit a myopic refraction shift or no significant myopic shift, for example subject exhibiting a refraction shift within -0,125 D and +0.25D ). Among them:
1 % (n=1 ) preferred the photopic value of vision correction power, 16% (n=18) had no preference.
Among the subjects who did prefer the mesopic value of vision correction power (91 % corresponding to 87 subjects),
55% (n=48) of them considered the difference of visual performance obtained with the mesopic value of vision correction power and the photopic value of vision correction power as being moderate to important.
45% (n=39) of them evaluated this difference in visual performance as a slight difference.
Among the subjects who did prefer the photopic value of vision correction power, the difference in visual performance was always noted as being slight.
The impact of dark adaptation time used during step b) of the method according to the invention was also evaluated when the subject is exposed to scotopic light conditions.
During the above described clinical study, for 82 subjects out of the 115 subjects, the method of the invention was applied with the optometry system of the invention, with two predetermined amounts of dark adaptation time of 2.5 minutes and 5 minutes in step b), the dark adaptation times being randomized.
In practice, for 82 out of the 115 subjects, the mesopic refraction protocol was used under the two above mentioned dark adaptation times randomly, at the same visit. The test luminance was moderate at 1 .1 cd/m2. A re-adaptation time to photopic light levels was conducted between dark adaptation times to ensure same retinal adaptation state before starting the mesopic refraction.
The results obtained with the two different dark adaptation times were compared. The 82 subjects comprised 50 non-presbyopes persons and 32 presbyopes persons.
The same refraction test unit was used with 1.1 cd/m2 mesopic visual optotype background luminance. The dark adaptation time is the only variable parameter for this comparison.
The results obtained are shown on figure 11 that relates to the values of refined mesopic refraction shift measured after (left) 5 minutes and (right) 2.5 minutes of dark adaptation prior the mesopic refraction test and on figure 13 that concerns the values of mesopic visual acuity gain measured while the individual is provided with the mesopic value of the vision correction, thus the refined mesopic shift being compensated, after (left) 5 minutes and (right) 2.5 minutes of dark adaptation before performing the mesopic refraction test.
The refined mesopic refraction shift measured with two different dark adaptation times (DA) used during the step b) are equivalent since the p-value is superior to 0.05 : p=0.89.
Figure 13 shows the visual acuity gain in mesopic light conditions due to compensation of refined mesopic refraction shift at two dark adaptation times, 5-min (left side) and 2.5min (right side). The subjects were provided with a test lens having a mesopic value of vision correction power.
The mean visual acuity gain is 0.06 logMAR (about 1 visual acuity line of ETDRS chart). No significantly difference is observed between the visual acuity gains measured with the two different dark adaptation times (p>0.05).
The results are the following:
- for the dark adaptation time of 5 minutes : the mean value of the refraction shift is -0.36 D with a standard deviation (SD) of 0,21 D, the median value of the refraction shift is -0.25 D with an interquartile range of 0.25 D, the range is -0.87 to 0.125D.
- for the dark adaptation time of 2.5 minutes : the mean value of the refraction shift is -0.37 D with a standard deviation (SD) of 0,23D, the median value of the refraction shift is -0.37 D with an interquartile range of 0.25 D, the range is -0.87 to 0.125D.
The p-value of 0.89 (>0.05) shows that the refraction shift obtained with a 2.5 min time dark adaptation and a 5 min time dark adaptation are not significantly different.
The visual acuity gain is also of about one line. The median value of the visual acuity gain with dark adaptation time of 5 min is -0.05 logMAR units. The median value of the visual acuity gain with dark adaptation time of 2.5 min is -0.06 logMAR (p=0.97).
These results allow to conclude that using a 2.5 min dark adaptation time in step b) of the method according to the invention provides comparable results (refraction shift and visual acuity gain) as using a 5 min dark adaptation time in step b).
Figure 12 shows a Bland-Altman's plots of agreement in refined mesopic refraction shift between two dark adaptation times, 5 min and a 2.5 min. On this figure 12, “Bias” is the average difference between both dark adaptation times and the 95% limits of agreement (LoA) is almost 2 SD from the average difference, more precisely 1.96 standard deviation.
According to the Bland-Altman's agreement plot of figure 12, mean difference between the two dark adaptation times is close to zero, exactly -0.01 D and the 95% limits of agreement are ±0.36D. Thus, 95% of the differences between the two dark adaptation times fall within +0.35D and -0.39D.
The following table illustrates the different groups of refined refraction shifts obtained in a sub-population of subjects taken from the clinical study described above.
The refraction shifts of 54 healthy and regular drivers (non presbyobes) included in the above mentioned study are determined using a dark adaptation time of 5 minutes. They include 38 women and 16 men.
Three groups of refraction shifts measured by the mesopic refraction test described above are found, as represented in table 1 . Table 1
Figure imgf000048_0001
Drivers rated better the lenses with mesopic value of vision correction power for visual tasks such as reading road signs, perception of light sources, judgement of road exit distances or judgement of distances with another vehicle, i.e. all of their visual tasks more related to central vision than to peripheral vision. Drivers also reported better global and far vision as well as satisfaction during their night driving activity.
The reproducibility of the method according to the invention has been assessed.
Reproducibility refers to the variability of the mesopic subjective refraction over time and this variability is related to many factors such as examiner performing the measurement, time past between measurements or time day (for instance day versus afternoon). Reproducibility is a measurement of precision or closeness agreement and whether over time a given method of measurement accurately measures what it aims to measure. Good reproducibility of a given methodology, for example a subjective refraction protocol, is used to validate said methodology. Reproducibility measurement is usually reported as the mean difference between measurements over time and the 95% limits of agreement which represents the distribution of difference between measurements and thus, the probability that 95% of difference fall within a range.
According to Bland-Altman's plot of figure 14, the mean differences calculated between two repeated measurements V1 and V2 over the time of mesopic refraction shift according to the invention, as illustrated on the figure 14, is -0.05 D and 95% limits of agreement is ±0.28 D. 95% of differences between the two measurements V1 and V2 over time fall within +0.23 D and -0.33 D.
On figure 14, “Biais” is the average difference between measurements and LoA is the 95% limits of agreement which is about two standard deviations from average difference, here 1.96 SD. The 54 subjects underwent a mesopic refraction test with 1.1 cd/m2 test luminance backgrounds and 5 minutes dark adaptation time. Average time between measurements is 60 days. The two measurements are performed by two different operator, at the same moment of the day.
Therefore, the mesopic refraction determination method according to the invention has been proven to be reproducible over time independently from the operator performing the subjective refraction determination or from the time past between two measurements.
According to the distribution and mean values of refined mesopic Rx shift of tested subjects as illustrated on the figure 15, 96 out of the 115 subjects (83%) showed a refined mesopic Rx shift equal or higher than -0.25D when changing light environment from photopic to mesopic conditions. The median value of the refined mesopic Rx shift of all subjects equals to -0.37D i.e. it could be detected even with classical phoropters having a step of 0.25D between two lenses of its array of lenses (IQR interquartile range is 0.25D). Moreover, for some subjects, the refined myopic Rx shifts goes up to values of -0.87D.
The invention also concerns any optical article designed such as to define a vision correction equals to the mesopic value of vision correction power determined with the optometry system and method according to the invention.
Said optical article can possibly include also a filter and/or an anti reflective coating known to be suited to improve an individual’s vision in mesopic lighting conditions and/or reduce glare.
For example, said optical article can comprise, in addition to the vision correction equals to the mesopic value of vision correction power determined with the optometry system and method according to the invention, any one of the following features considered alone or in combination:
- an antireflective coating on said front and rear faces having a luminous reflectance in the visible region for scotopic vision Rv' lower than or equal to 1 .5%;
- it lowers by at least 20% transmission of light emitted by a LED for wavelengths ranging from 380 nm to 500 nm;
- said antireflective coating on said front and rear faces has a luminous reflectance in the visible region for scotopic vision Rv' lower than or equal to 1 .0%, preferably lower than or equal to 0.7%, more preferably lower than or equal to 0.5%,
- said antireflective coating being as defined in table 2 below and as described in EP3629079 (Refractive indices are expressed at 25°C at a wavelength of 550 nm)
Figure imgf000050_0002
Table 2
- a light cut factor CutLED of at least 20% for wavelengths ranging from
380 nm to 500 nm, CutLED being defined by:
CutLED = 100
Figure imgf000050_0001
where Z is a discrete or continuous sum operator, A is the wavelength in nm, lens T% is the transmittance of said lens in % and LED emission% is the spectral distribution of a white light emitting diode in %,
- it contains light absorbing dyes, more preferably, it comprises a substrate and said light absorbing dyes are located in the mass of said substrate, or in a thin layer of the mass of the substrate of the lens.
Light cut behavior is mainly achieved through absorption with absorbing dyes deposited through an imbibition or a sublimation method, wherein the tinting recipe is balanced to achieve the desired value of CutLED while maintaining sufficiently high transmittance Tv and a sufficiently neutral colour. More preferably, dyes are deposited by sublimation on lens substrates with a mixture of three sublimable dyes (blue, yellow and red to yield a brown colour) printed on a specific paper, dyes being transferred from the specific paper to the concave side of the lens by sublimation, the lens being finally heated so that dyes diffuse in the mass of the lens (imbibiting step), ideally with the resulting optical properties as disclosed in the below Table 3.
Figure imgf000051_0001
Table 3
The optical article can be as described in the embodiment L3 or L4 of EP3629079, with optical properties as disclosed in the Table 3.
The invention furthermore concerns any set of optical articles including a first optical article designed such as to define a vision correction equals to the photopic vision correction, and a second optical article according to the invention.
More precisely, such a set of optical articles can include for example a first optical article such as an ophthalmic lens designed with the photopic vision correction power, and a second optical article such as an ophthalmic lens designed with the refined mesopic vision correction power, optionally comprising an antireflective coating and/or a tint as defined previously. As an alternative, the second optical article can consist in a clip adapted to be removably associated with the first optical article and to define with the latter a global vision correction that equals to the refined mesopic value of vision correction, the clip associated with each eye of the individual being designed with a sphere calculated or equal to the corresponding refined mesopic shift determined thanks to the system and method according to the invention.
A vision correction lens or set of optical articles, may then be manufactured with said mesopic vision correction power.

Claims

1. Optometry system for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions, said system comprising an optometry device having a refraction test unit with two optical refraction elements, each optical refraction element being adapted to provide test values of said vision correction power to one of the eyes of the individual, said optometry system comprising a computer with one or more processors programmed to: a) control the optometry device to determine a photopic value of said vision correction power of said corrective lens for each eye of said individual by achieving a photopic subjective refraction test in light conditions ensuring photopic vision of the eyes of the individual, or to retrieve an initial vision correction value stored in a memory of the optometry system, or to collect an initial vision correction value, b) validate a step of placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time, c) validate a step of placing the eyes of the individual in light conditions ensuring mesopic vision of the eyes of the individual and d) control the optometry device to achieve a mesopic subjective refraction test, said mesopic subjective refraction test comprising:
- fogging both eyes by providing to each eye a fogging test value of vision correction power equal to a predetermined fogging spherical power added to the corresponding photopic value of the vision correction power,
- iteratively adding to both eyes a same negative predetermined value of spherical power to said fogging test value and determining, each time said negative predetermined value of spherical power is added, a mesopic binocular visual acuity of the eyes until a maximum value of the mesopic binocular visual acuity is reached, thereby determining for each eye a mesopic raw value of the vision correction power equal to a test value of the vision correction power associated to the maximum value of the mesopic binocular visual acuity, e) determining, for each eye of the individual, said mesopic value of vision correction power based on said mesopic raw value of the vision correction power.
2. Optometry system according to claim 1 , wherein said one or more processors are programmed to perform, in step e), a final mesopic visual appreciation test with the following steps:
- controlling the optometry device for providing each eye of the individual with the mesopic raw value of the vision correction power determined in step d),
- for each eye, controlling the optometry device for adding a predetermined negative value of spherical power to said mesopic raw value of the vision correction power and collecting an answer of the individual asked to compare his visual performance with and without the added predetermined negative value of spherical power,
- based on this comparison, determining said mesopic value of vision correction power for each eye of the individual by adding a refining value of spherical power to said mesopic raw value of the vision correction power for each eye, aiming at improving the quality of mesopic vision and depending on said predetermined negative value of spherical power.
3. Optometry system according to claim 2, wherein, the refining value of spherical power added by said one or more processors comprises one of the following :
- said predetermined negative value of spherical power,
- a positive or negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power
- a null value.
4. Optometry system according to claim 3, wherein, when said comparison shows no difference in the visual performance of the eyes of the individual, said one or more processors are programmed to add the refining value of spherical power equal to said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power.
5. Optometry system according to any one of claims 3 or 4, wherein, when said comparison shows a difference in the visual performance of the eyes of the individual, said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and: - when said answer indicates a slight or moderate difference in the visual performance of the eyes of the individual in favor of his visual performance with the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power
6. Optometry system according to any one of claims 4 or 5, wherein said one or more processors are programmed to determine said negative value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power as being equal to a fraction of the predetermined negative value of spherical power.
7. Optometry system according to any one of claims 3 to 6, wherein, when said comparison shows a difference in the visual performance of the eyes of the individual, said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and :
- when said answer indicates an important difference in the visual performance of the eyes of the individual in favor of his visual performance with the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said predetermined negative value of spherical power
8. Optometry system according to any one of claims 3 to 7, wherein, when said comparison shows a difference in the visual performance of the eyes of the individual, said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and :
- when said answer indicates a slight or moderate difference in the visual performance of the eyes of the individual in favor of his visual performance without the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said null value.
9. Optometry system according to any one of claims 3 to 8, wherein, when said comparison shows a difference in the visual performance of the eyes of the individual, said one or more processors are programmed to request an input of an answer of said individual asked to assess the difference by qualifying it of slight, moderate or important, and :
- when said answer indicates an important difference in the visual performance of the eyes of the individual in favor of his visual performance without the added predetermined negative value of spherical power, said one or more processors are programmed to add the refining value of spherical power equal to said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power.
10. Optometry system according to claim 9, wherein said one or more processors are programmed to determine said positive value of spherical power having an absolute value smaller than the absolute value of the predetermined negative value of spherical power as being equal to a fraction of the absolute value of said predetermined negative value of spherical power.
11 . Optometry system according to any one of claims 1 to 10, wherein said one or more processors are programmed to determine, in step d) or e), a binocular visual acuity of the eyes, each eye being provided with the corresponding photopic value of the vision correction power determined in step a).
12. Optometry system according to any one of claims 1 to 11 , wherein said one or more processors are programmed to perform a step of evaluation of the visual performances of the subject while his eyes are placed in light conditions ensuring mesopic vision and provided either with the photopic value of the vision correction power determined in step a) or with the mesopic value of the vision correction power determined in step e).
13. Optometry system according to any of claims 1 to 11 , wherein said one or more processors are programmed to validate said step of placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual with said predetermined amount of time being comprised between 2 minutes and 10 minutes, more preferably between 2 minutes and 5 minutes, more preferably equals to 2.5 minutes.
14. Optometry system according to any of claims 1 to 12, wherein the optometry system comprises an input device for collecting the answers of the individual and wherein said one or more processors are programmed to set each next test value provided by said optical refraction element according to the last answer collected by said input device from the individual.
15. Optometry system according to any of claims 1 to 13, wherein the optometry system comprises a screen adapted to display vision tests and wherein said one or more processors are programmed to control the luminance of the screen depending on the light conditions ensuring photopic, scotopic and mesopic vision in which the eyes of the individual are placed.
16. Method for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens to be worn by the individual in mesopic light conditions, using an optometry device having a refraction test unit with two optical refraction elements, each optical refraction element being adapted to provide test values of said vision correction power to one of the eyes of the individual, said method comprising the following steps: a) determining a photopic value of said vision correction power of said corrective lens for each eye of said individual by achieving a photopic subjective refraction test in light conditions ensuring photopic vision of the eyes of the individual, b) placing the eyes of the individual in light conditions ensuring scotopic vision of the eye of the individual for a predetermined amount of time, c) placing the eyes of the individual in light conditions ensuring mesopic vision of the eyes of the individual and d) achieving a mesopic subjective refraction test, said mesopic subjective refraction test comprising:
- determining a binocular visual acuity of the eyes, each eye being provided with the corresponding photopic value of the vision correction power determined in step a),
- fogging both eyes by providing to each eye a fogging test value of vision correction power equal to a predetermined fogging spherical power added to the corresponding photopic value of the vision correction power,
- iteratively adding to both eyes a same negative predetermined value of spherical power to said fogging test value and determining, each time said negative predetermined value of spherical power is added, a mesopic binocular visual acuity of the eyes until a maximum value of the mesopic binocular visual acuity is reached, thereby determining for each eye a mesopic raw value of the vision correction power equal to a test value of the vision correction power associated to the maximum value of the mesopic binocular visual acuity, e) determining, for each eye of the individual, said mesopic value of vision correction power based on said mesopic raw value of the vision correction power.
PCT/EP2024/053908 2023-02-17 2024-02-15 Optometry system for determining, for each eye of an individual, a mesopic value of a vision correction power of a corrective lens Ceased WO2024170703A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN120000146A (en) * 2024-09-27 2025-05-16 中国人民解放军空军军医大学 A rapid method for testing dark adaptation function of mesopic vision

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5430510A (en) * 1991-08-01 1995-07-04 Opsia Equipment for testing visual acuity and/or sensitivity to spatial contrasts in humans, and a corresponding device and manufacturing process
JP3850186B2 (en) * 1999-09-27 2006-11-29 株式会社ニデック Night vision meter
US9072434B2 (en) * 2012-02-20 2015-07-07 Indiana University Research & Technology Corporation Methods, systems and apparatuses for night and day corrective ophthalmic prescription
EP3298952A1 (en) 2016-09-22 2018-03-28 Essilor International Optometry device
EP3298951A1 (en) 2016-09-22 2018-03-28 Essilor International Optometry device and method of performing a test using such an optometry device
EP3629079A1 (en) 2018-09-27 2020-04-01 Essilor International An ophthalmic lens for improving night driving vision and a method for obtaining the same
US20200205656A1 (en) * 2018-12-31 2020-07-02 Rxsight, Inc. Multi-factor control system for ophthalmic refraction modification
EP3711654A1 (en) 2019-03-20 2020-09-23 Essilor International Optometry device for testing an individual's eye and associated method
EP4231892A1 (en) 2020-10-22 2023-08-30 Essilor International Optometry device for testing an individual's eyes, set of pictures for said device and display unit of such set of pictures

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5430510A (en) * 1991-08-01 1995-07-04 Opsia Equipment for testing visual acuity and/or sensitivity to spatial contrasts in humans, and a corresponding device and manufacturing process
JP3850186B2 (en) * 1999-09-27 2006-11-29 株式会社ニデック Night vision meter
US9072434B2 (en) * 2012-02-20 2015-07-07 Indiana University Research & Technology Corporation Methods, systems and apparatuses for night and day corrective ophthalmic prescription
EP3298952A1 (en) 2016-09-22 2018-03-28 Essilor International Optometry device
EP3298951A1 (en) 2016-09-22 2018-03-28 Essilor International Optometry device and method of performing a test using such an optometry device
EP3629079A1 (en) 2018-09-27 2020-04-01 Essilor International An ophthalmic lens for improving night driving vision and a method for obtaining the same
US20200205656A1 (en) * 2018-12-31 2020-07-02 Rxsight, Inc. Multi-factor control system for ophthalmic refraction modification
EP3711654A1 (en) 2019-03-20 2020-09-23 Essilor International Optometry device for testing an individual's eye and associated method
EP4231892A1 (en) 2020-10-22 2023-08-30 Essilor International Optometry device for testing an individual's eyes, set of pictures for said device and display unit of such set of pictures

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN120000146A (en) * 2024-09-27 2025-05-16 中国人民解放军空军军医大学 A rapid method for testing dark adaptation function of mesopic vision

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