WO2025133168A1

WO2025133168A1 - Method of ophthalmic lens thicknesses management

Info

Publication number: WO2025133168A1
Application number: PCT/EP2024/087972
Authority: WO
Inventors: Mélanie HESLOUIS; Olivier Roussel; Samy HAMLAOUI
Original assignee: Essilor International Compagnie Generale dOptique SA
Current assignee: EssilorLuxottica SA
Priority date: 2023-12-22
Filing date: 2024-12-20
Publication date: 2025-06-26
Anticipated expiration: 2026-06-22

Abstract

The disclosure relates to a for adapting thickness of an initial lens based on peripheral thickness or width determined constraint Said determined constraint enable to determine a target zone of the initial lens to be modified. Said lens being modified over the targeted zone so as to fulfill the peripheral determined constraint.

Description

Method of ophthalmic lens thicknesses management

TECHNICAL FIELD

[0001] The disclosure relates to ophthalmic lens design. More particularly, the disclosure relates to the design of an ophthalmic lens involving its geometry of the ophthalmic lens over a peripheral portion.

BACKGROUND

[0002] Some of the existing ophthalmic lenses are known to involve aesthetic and mechanical issues.

[0003] Aesthetic disagreement may occur over the temporal side for myopic wearers. The aesthetic disagreement occurs on the nasal side for hyperopic wearers, for example due to the nose pad position for ophthalmic lens having a thick nasal portion.

[0004] A first mechanical issue is directed to the absence of total closing/fold of the temples of an eyewear for myopic wearer having ophthalmic lenses with thick temporal edges.

[0005] A second mechanical issue is related to the complexity to position the bevel on the peripheral portion of an ophthalmic lens due to the variability of the edge thickness.

[0006] A third issue is relative to the contact between the ophthalmic lens and the frame, more particularly at the location of the nose pads, temple and hinge. This can result in risk of damages of the ophthalmic lens as the location of the contact between the lens and the frame for example for myopic wearers eyewear.

[0007] The aim of the present disclosure is to provide a solution to the above listed problem without impacting the optical function of the ophthalmic lens to be provided to the wearer.

SUMMARY OF THE DISCLOSURE

[0008] To this end, the disclosure relates to a method for adapting thickness of an initial lens, the method comprising: • an initial lens data obtaining step SI, wherein the initial lens data comprises: o a contour of the lens configured to be mounted in a frame, o a shape of the front face, o a shape of the rear face, o positioning of the front face relative to the rear face, o a position of a center point O on the rear face of the lens, being the point of the lens through which a wearer is configured to gaze in a main gaze direction when wearing the lens when being mounted in said frame, and o an optical power provided at least at the center point O,

• a portion of the contour determining step S2, wherein a portion of the contour of the initial lens to be modified is determined, said portion of the contour having two extremities Pl, P2, said contour portion CPI,P2 being defined in a cylindrical referential (Q, 9) centered in

O, where Pl coordinates are (QI, 0i) and P2 coordinates are (Q2, 02),

• a constraint determining step S3, wherein said determined constraint is: o a thickness constraint defined by a thickness profile T(0), wherein said thickness profile T(0) associates a required thickness constraint T(0i) at any point Pi (Qi, 0i) of the portion of the contour CPI,P2 between the extremities Pl, P2 wherein the thickness constraint in points Pl, P2, T(0i) and T(02) is equal to the thickness of the initial lens in points Pl, P2. or o a width constraint defined by a width profile W(0), wherein said width profile W(0) associates a required width constraint W(0i) at any point Pi, wherein W(0i) is a distance separating Pi (Qi,0i) and Pi’ ( i’,0i), with P< Qi, wherein W(0i) and W(02) is equal to 0,

• a variation law determining step S4, wherein a variation law TV(0) is determined at least based on the determined constraint,

• a target zone determination step S5, wherein a target zone of the initial lens is determined based on the determined constraint of step S3 or on the variation law TV(0),

• a modification step S6, wherein the initial lens is modified over the target zone, so as to fulfill the determined constraint and the variation law TV(0) for any of the point Pi, and

• a final lens providing step S7, wherein a final lens being the lens resulting from step S6. [0009] Advantageously, such method enables to address the aesthetic and mechanical issues mentioned above. By adapting the thickness over the peripheral portion of the lens, a better housing of the ophthalmic lens can be performed without requiring the formation of a step. A step is unesthetic and may weaken the ophthalmic lens at the location where the thickness is the thinnest.

[0010] Advantageously, the method according to the disclosure enables to produce ophthalmic lens with modified rear and/or front face over the peripheral portion without introducing any optical disturbance in the central portion of the lens, for example a disk centered over the optical cent of the rear face of the lens and having a radius greater or equal to 15 mm and smaller or equal to 25 mm, preferably equal to 20 mm. Said disk may correspond to the intersection on the rear face of a cone of vision having a generatrix being the main gaze direction. Said cone having for example a cone aperture angle may be bigger or equal to 30°, lower or equal to 50°, preferably equal 40°.

[0011] Preferably, the target area may be located on the temporal and/or nasal area to ease the accommodation within the frame of the eyewear.

[0012] According to further embodiments of the method which can be considered alone or in combination:

- the target zone is projected on the rear face of the initial lens; and/or

- the determined constraint according to step S3 is the width constraint defined by a width profile W(0), and wherein the variation law TV(0) is a thickness profile derived from: o the width profile W(0), and o a curvature variation law Ce(g); and/or providing wherein the target zone is delimited on one hand by the portion of the contour CPI,P2 and on the other hand by the width profile W(0); and/or

- the determined constraint according to step S3 is the thickness constraint defined by a thickness profile T(0), and wherein the variation law TV(0) is a width profile derived from: o the thickness profile T(0), and o a curvature variation law Ce(g) wherein said width profile TV(0) associates a required width constraint TV(0i) at any point Pi, wherein TV(00 is a distance separating Pi (Qi, 90 and Pi’ (Qi’, 90, with Qi’ < Qi; and/or

- the target zone is delimited on one hand by the portion of the contour CPI,P2 and on the other hand by the width profile TV(9); and/or

- the target zone is a subzone of a zone delimited on one hand by the portion of the contour CPI,P2, and on the other hand by the width profile W(9) or the width profile formed by the variation law TV(9), void of the surface of a disk centered in O and having a radius R intersecting said delimited zone; and/or the radius R depends on the sensibility of the wearer; and/or

- the curvature variation law CO(Q) is continuous; and/or

- wherein for each point Pi’ (Qi’, 90 obtained from: o the with profile W(00, relative to the point Pi (Qi, 90, or o the variation law TV(00, when the determined constraint is the thickness constraint,

Cei(Qi’) is equal to the curvature Cei(Qi’) of the initial lens in said point Pi’; and/or

- the curvature variation law Cei( ) is defined based on two criterions: o the final curvature Cei(Q0 at the point Pi, and o the minimum curvature value minCoi(Q); and/or for any point N of the rear face of the modified initial lens according to step S6, a thickness, being the distance between said point N and its projection N’ on the front face according to a direction defined by the axis normal to the rear face in O, determining the minimum thickness TN of the modified initial lens, if the minimum thickness TN of the final lens is superior to a thickness threshold Tth, the method further comprises, after modification step S6 and before the final lens providing step S7,a thickness optimizing step S8 being the offset of the rear face relative to the front face in the projection direction, by the amount of the difference of the minimum thickness of the modified initial lens according to step S6 TN minus the thickness threshold Tth.

[0013] Another object of the disclosure is a computer program product comprising one or more stored sequences of instructions which, when executed by a processing unit, are able to perform the method according to the disclosure.

[0014] The disclosure further relates to a computer program product comprising one or more stored sequences of instructions that are accessible to a processor and which, when executed by the processor, causes the processor to carry out at least the steps of the method according to the disclosure.

[0015] The disclosure also relates to a computer-readable storage medium having a program recorded thereon; where the program makes the computer execute at least the steps of the method of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Non limiting embodiments of the disclosure will now be described, by way of example only, and with reference to the following drawings in which:

- Figures 1 and 2 show, diagrammatically, optical systems of eye and lens and ray tracing from the center of rotation of the eye;

- Figure 3 is a flowchart of the method according to the disclosure;

- Figures 4 to 7 are rear views of an ophthalmic lens according to the disclosure;

- Figures 8 is graph of the variation of the thickness over a portion of the contour of the ophthalmic lens to be modified;

- Figures 9 is graph of the variation of the width over the rear face the ophthalmic lens to be modified;

- Figure 10 illustrates the variation of the thickness for an angular direction between an initial lens and a lens according to the disclosure for a myopic wearer;

- Figure 11 illustrates the variation of the thickness for an angular direction between an initial lens and a lens according to the disclosure for a hyperopic wearer;

- Figure 12 illustrates the variation of the altitude for an angular direction;

- Figure 13 illustrates the variation of the curvature for an angular direction;

- Figure 14 illustrates a width variation profile according to a first embodiment;

- Figure 15 illustrates a profile of the curvature for an angular direction according to said first embodiment;

- Figure 16 illustrates a thickness profile according to said first embodiment;

- Figure 17 illustrates a thickness variation along the frame contour with respect to the initial lens according to said first example;

- Figure 18 illustrates a thickness variation for an angular direction with respect to the initial lens according to said first example;

- Figure 19 illustrates a width variation profile according to a second example; - Figure 20 illustrates a profile of the curvature for an angular direction according to said second example;

- Figure 21 illustrates a thickness profile according to said second example;

- Figure 22 illustrates a thickness variation along the frame contour with respect to the initial lens according to said second example;

- Figure 23 illustrates a thickness variation along the frame contour with respect to the initial lens according to said second example after optimization;

- Figure 24 illustrates a profile of the curvature for an angular direction according to said third example;

- Figure 25 illustrates a thickness profile according to said third example;

- Figure 26 illustrates a width profile according to said third example;

- Figure 27 illustrates a thickness variation along the frame contour with respect to the initial lens according to said third example;

- Figure 28 illustrates a thickness variation for an angular direction with respect to the initial lens according to said third example;

- Figure 29 illustrates a profile of a width according to a wearer sensitivity level according to a fourth example;

- Figure 30 illustrates a profile of a width and a cone aperture according to a fifth example;

- Figure 31 illustrates a rear face of lens according to a sixth example;

- Figures 32 illustrates a rear face of lenses according to a seventh example;

- Figure 33 illustrates the variation of width according to the lens total width according to the seventh example;

- Figure 34 illustrates the variation of width according to the lens total width according to an eighth example;

Figure 35 illustrates the variation of radius according to the lens total width according to an eighth example;

- Figure 36 illustrates the variation of the cone aperture based on the prescription of the wearer according to a nineth example; and

- Figure 37 illustrates the rear face of a lens. DEFINITIONS

[0017] The following definitions are provided so as to define the wordings used within the frame of the present disclosure.

[0018] The wordings "wearer's prescription", also called "prescription data", are known in the art. Prescription data refers to one or more data obtained for the wearer and indicating for at least an eye, preferably for each eye, a prescribed sphere SPHp, and/or a prescribed astigmatism value CYLp and a prescribed axis AXISp suitable for correcting the ametropia of each eye for the wearer and a prescribed addition Add suitable for correcting the presbyopia of each of his eyes. The prescribed optical data, such as the prescribed optical power, the prescribed addition and/or the prescribed astigmatism, is transmitted by the ECP when he/she orders the ophthalmic lens to an ophthalmic lens manufacturer.

[0019] The prescribed optical power may comprise the prescribed far vision power corresponding to the optical power provided to the wearer to correct the visual impairment when the wearer is gazing at far distance.

[0020] The prescribed optical power may comprise the prescribed near vision power corresponding to the optical power provided to the wearer to correct the visual impairment when the wearer is gazing at near distance.

[0021] The ophthalmic lens manufacturer prescribed addition usually inscribes information relative to the prescribed addition on the paper packaging of the delivered lens. The prescribed addition may be also determined from engravings located on the ophthalmic lens and still visible after the ophthalmic lens is edged and when mounted in said spectacle frame chosen by the wearer.

[0022] "Progressive ophthalmic addition lenses" are known in the art. According to the disclosure, the ophthalmic lens may be an unedged ophthalmic lens or a spectacle lens edged to be mounted in a spectacle frame. The ophthalmic lens may also be suitable for sunglasses. All ophthalmic lenses of the disclosure may be paired so as to form a pair of lenses (left eye LE, right eye RE).

[0023] The wording “optical design” is a widely used wording known from the man skilled in the art in ophthalmic domain to designate the set of parameters allowing to defining an optical function of an ophthalmic lens. Each ophthalmic lens designer has its own designs, particularly for progressive ophthalmic lenses. As for an example, a progressive ophthalmic lens “design” results of an optimization of a progressive surface so as to restore a presbyope’s ability to see clearly at all distances but also to optimally respect all physiological visual functions such as foveal vision, extra-foveal vision, binocular vision, dynamic vision and to minimize unwanted astigmatisms. For example, a progressive lens design comprises: a power profile along the main gaze directions (meridian line) used by the ophthalmic lens wearer during day life activities, distributions of powers (mean power, astigmatism,...) on the sides of the ophthalmic lens, that is to say away from the main gaze direction.

[0024] These optical characteristics are part of the "designs" defined and calculated by ophthalmic lens designers and that are provided with the progressive lenses.

[0025] A "gaze direction" is identified by a couple of angle values (a,P), wherein said angles values are measured with regard to reference axes centered on the center lens O. More precisely, figure 1 represents a perspective view of an ophthalmic lens 1 and illustrating parameters a and P used defining a gaze direction. The angle alpha shown in figure 1 has a negative value. The main gaze direction may be defined for the couple of a angle values (a = 0°, p = 0°)

[0026] In other embodiments, as illustrated on figures 8a to 16b, the reference axes are centered on the lens fitting point.

[0027] Figure 2 is a view in the vertical plane parallel to the antero-posterior axis of the wearer's head and passing through the center of rotation of the eye in the case when the parameter p is equal to 0. The center of rotation of the eye is labeled Q’. The axis Q’-F', shown on Figure 2 in a dot-dash line, is the horizontal axis passing through the center of rotation of the eye and extending in front of the wearer - that is the axis Q’-F' corresponding to the primary gaze direction. The ophthalmic lens is placed and centered in front of the eye such that the axis Q’-F' cuts the front face of the ophthalmic lens on a point called the fitting cross, which is, in general, present on lenses to enable the positioning of lenses in a frame by an optician. The point of intersection of the rear face of the ophthalmic lens and the axis Q’-F' is the point, O. A vertex sphere, which center is the center of rotation of the eye, Q’, and has a radius q' = O-Q’, intercepts the rear face of the ophthalmic lens in a point of the horizontal axis. A value of radius q' of 25.5 mm corresponds to a usual value and provides satisfying results when wearing the ophthalmic lenses. Other value of radius q' may be chosen. A given gaze direction, represented by a solid line on figure 1, corresponds to a position of the eye in rotation around Q’ and to a point J (see figure 2) of the vertex sphere.

[0028] The angle P is the angle formed between the axis Q’-F' and the projection of the straight line Q’-J on the horizontal plane comprising the axis Q’-F'; this angle appears on the scheme on Figure 1.

[0029] The angle a is the angle formed between the axis Q’-J and the projection of the straight line Q’-J on the horizontal plane comprising the axis Q’-F'; this angle appears on the scheme on Figures 1 and 2.

[0030] A given gaze direction thus corresponds to a point J of the vertex sphere or to a couple (a,P). The more the value of the lowering gaze angle a is positive, the more the gaze is lowering and the more the value is negative, the more the gaze is rising. In a given gaze direction, the image of a point M in the object space, located at a given object distance, is formed between two points S and T corresponding to minimum and maximum distances JS and JT, which would be the sagittal and tangential local focal lengths. The image of a point in the object space at infinity is formed, at the point F'. The distance D corresponds to the rear frontal plane of the ophthalmic lens.

[0031] For each gaze direction (a,P), a mean refractive power PPO(a,P), a module of astigmatism AST(a,P) and an axis AXE(a,P) of this astigmatism, and a module of resulting (also called residual or unwanted) astigmatism ASR(a,P) are defined.

[0032] "Astigmatism" refers to astigmatism generated by the ophthalmic lens, and “unwanted astigmatism” or resulting astigmatism corresponds to the difference between the ophthalmic lens-generated astigmatism and the prescribed astigmatism (wearer astigmatism); in each case, with regards to amplitude or both amplitude and axis.

[0033] In the sense of the disclosure, an “optical function” corresponds to a function providing for each gaze direction the effect of an optical lens on the light ray passing through the optical lens.

[0034] The optical function may comprise dioptric function, light absorption, polarizing capability, reinforcement of contrast capacity, etc. . . [0035] The dioptric function corresponds to the optical lens power (mean power, astigmatism etc. . . ) as a function of the gaze direction.

[0036] "Ergorama" is a function associating to each gaze direction the usual distance of an object point. Typically, in far vision following the primary gaze direction, the object point is at infinity. In near vision, following a gaze direction essentially corresponding to an angle a of the order of 35° and to an angle P of the order of 5° in absolute value towards the nasal side, the object distance is of the order of 30 to 50 cm. For more details concerning a possible definition of an ergorama, US patent US-A-6, 318,859 may be considered. This document describes an ergorama, its definition and its modeling method.

[0037] For the purpose of the disclosure, points may be at infinity or not. Ergorama may be a function of the wearer's ametropia. Using these elements, it is possible to define a wearer optical power and astigmatism, in each gaze direction. An object point M at an object distance given by the ergorama is considered for a gaze direction (a,P). An object proximity ProxO is defined for the point M on the corresponding light ray in the object space as the inverse of the distance MJ between point M and point J of the vertex sphere:

ProxO = 1 /MJ

[0038] This enables to calculate the object proximity within a thin lens approximation for all points of the vertex sphere, which is used for the determination of the ergorama. For a real lens, the object proximity can be considered as the inverse of the distance between the object point and the front face of the ophthalmic lens, on the corresponding light ray.

[0039] For the same gaze direction (a,P), the image of a point M having a given object proximity is formed between two points S and T which correspond respectively to minimal and maximal focal distances (which would be sagittal and tangential focal distances). The quantity Proxl is called image proximity of the point M:

[0040] By analogy with the case of a thin lens, it can therefore be defined, for a given gaze direction and for a given object proximity, i.e. for a point of the object space on the corresponding light ray, an optical power PPO as the sum of the image proximity and the object proximity. PPO = ProxO + Proxl

[0041] The optical power is also called refractive power.

[0042] With the same notations, an astigmatism AST is defined for every gaze direction and for a given object proximity

1 1

AST =

1T ~JS

[0043] This definition corresponds to the astigmatism of a ray beam created by the ophthalmic lens. The resulting astigmatism ASR is defined for every gaze direction through the ophthalmic lens as the difference between the actual astigmatism value AST for this gaze direction and the prescribed astigmatism. The unwanted astigmatism (resulting astigmatism) ASR more precisely corresponds to module of the vectorial difference between actual (AST, AXE) and prescription data (CYLp, AXISp).

[0044] When the characterization of the ophthalmic lens is of optical kind, it refers to the ergorama-eye-lens system described above. For simplicity, the term “lens” is used in the description but it has to be understood as the “ergorama-eye-lens system”. The values in optic terms can be expressed for gaze directions. Conditions suitable to determine of the ergorama- eye-lens system are called in the frame present disclosure "given wearing conditions".

[0045] In the remainder of the description, terms like « up », « bottom », « horizontal », «vertical », « above », « below », or other words indicating relative position may be used. These terms are to be understood in the wearing conditions of the ophthalmic lens. Notably, the "upper" part of the ophthalmic lens corresponds to a negative lowering angle a <0° and the "lower" part of the ophthalmic lens corresponds to a positive lowering angle a >0°.

[0046] A "far-vision gaze direction" is defined for an ophthalmic lens, as the vision gaze direction corresponding to the far vision (distant) reference point. Within the present disclosure, far-vision is also referred to as distant-vision. In the sense of the disclosure far vision is to be understood as vision at a distance greater than or equal to 4 meters.

[0047] A "near-vision gaze direction" is defined for an ophthalmic lens, as the vision gaze direction corresponding to the near vision (reading) reference point. In the embodiment of a progressive addition lens, the refractive power is substantially equal to the prescribed power in far vision plus the prescribed addition Add. In the sense of the disclosure near vision is to be understood as vision at a distance smaller than or equal to 50 cm. Here “substantially equal” means a “equal with a tolerance of at most 15%”. In this manner, a distance up to 57.5 cm is considered as a near vision distance.

[0048] An “intermediate-vision gaze direction” is defined for an ophthalmic lens, as the vision gaze direction corresponding to the intermediate vision (a person working in front of its computer desktop). In the sense of the disclosure intermediate vision is to be understood as vision at a distance greater than 50 cm, for example greater than 70 cm, and smaller than 4 meters, for example smaller than 1.5 m.

[0049] The "meridian line", referred as ML(a,P), of a progressive addition lens is a line defined from top to bottom of the ophthalmic lens and passing through the fitting cross where one can see clearly an object point. Said meridian line is defined on the basis of the repartition of module of resulting astigmatism, ASR, over the (a, P) domain and substantially correspond to the center of the two central iso-module of resulting astigmatism values which value is equal to 0.5 D.

[0050] The “wearing conditions” are to be understood as the position of the ophthalmic lens with relation to the eye of a wearer, for example defined by a pantoscopic angle, a Cornea to lens distance, a Pupil-cornea distance, a CRE to pupil distance, a CRE to lens distance and a wrap angle.

[0051] The Cornea to lens distance is the distance along the visual axis of the eye in the primary position (usually taken to be the horizontal) between the cornea and the rear face of the ophthalmic lens; for example equal to 12mm.

[0052] The Pupil-cornea distance is the distance along the visual axis of the eye between its pupil and cornea; usually equal to 2mm.

[0053] The CRE to pupil distance is the distance along the visual axis of the eye between its center of rotation (CRE) and pupil; for example equal to 11.5mm.

[0054] The CRE to lens distance is the distance along the visual axis of the eye in the primary position (usually taken to be the horizontal) between the CRE of the eye and the rear face of the ophthalmic lens, for example equal to 25.5mm. [0055] The pantoscopic angle is the angle in the vertical plane, at the intersection between the rear face of the ophthalmic lens and the visual axis of the eye in the primary position (usually taken to be the horizontal), between the normal to the rear face of the ophthalmic lens and the visual axis of the eye in the primary position ; for example equal to -8°.

[0056] The wrap angle is the angle in the horizontal plane, at the intersection between the rear face of the ophthalmic lens and the visual axis of the eye in the primary position (usually taken to be the horizontal), between the normal to the rear face of the ophthalmic lens and the visual axis of the eye in the primary position for example equal to 0°.

[0057] An example of standard wearing condition may be defined by a pantoscopic angle of -8°, a Cornea to lens distance of 12 mm, a Pupil-cornea distance of 2 mm, a CRE to pupil distance of 11.5 mm, a CRE to lens distance of 25.5 mm and a wrap angle of 0°.

[0058] The variation law is a function that adjusts the constraints profile, for example thickness or width profiles, in response to wearer-specific and frame-specific parameters, such as wearer sensitivity, frame size, and mounting specifications. This law enables the adaptation of the constraints profiles to optimize comfort and fit, tailored to frame characteristics and possibly to individual wearer.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0059] Figure 3 illustrates a flowchart of the method according to the disclosure of a method for adapting thickness of an initial lens 1, the method comprising:

• an initial lens data obtaining step SI, wherein the initial lens data comprises: o a contour of the lens configured to be mounted in a frame, o a shape of the front face 10, o a shape of the rear face 12, o positioning of the front face 12 relative to the rear face 10, o a position of a center point O on the rear face 10 of the lens 1, being the point of the lens through which a wearer is configured to gaze in a main gaze direction when wearing the lens when being mounted in said frame, and o an optical power provided at least at the center point O, • a portion of the contour determining step S2, wherein a portion of the contour of the initial lens to be modified is determined, said portion of the contour having two extremities Pl, P2, said contour portion CPI,P2 being defined in a cylindrical referential (Q, 9) centered in O, where Pl coordinates are (QI, 0i) and P2 coordinates are (Q2, 02),

• a constraint determining step S3, wherein said determined constraint is: o a thickness constraint defined by a thickness profile T(0), wherein said thickness profile T(0) associates a required thickness constraint T(0i) at any point Pi (Qi, 0i) of the portion of the contour CPI,P2 between the extremities Pl, P2 wherein the thickness constraint in points Pl, P2, T(0i) and T(02) is equal to the thickness of the initial lens in points Pl, P2. or o a width constraint defined by a width profile W(0), wherein said width profile W(0) associates a required width constraint W(0i) at any point Pi, wherein W(0i) is a distance separating Pi (Qi,0i) and Pi’ (Qi’,0i), with P< Qi, wherein W(0i) and W(02) is equal to 0,

• a final lens providing step S7, wherein a final lens being the lens resulting from step S6.

[0060] The method firstly comprises an initial lens data obtaining step SI, wherein structural and optical features of an initial lens is obtained.

[0061] The initial lens can be an ophthalmic lens.

[0062] Said initial lens has a contour configured to be mounted in the frame of an eyewear equipment.

[0063] The shape of the front and rear face of the lens are defined by their respective contour and the curvature in any point of the surfacic area defined by the front and the rear faces. [0064] The positioning of the front face relative to the rear face comprises the spacing of the rear face with respect to the front face of the initial lens according to the direction normal to the center point O of the rear face. The positioning also comprises the orientation of the front face with respect to the rear face defined as prism.

[0065] The center point O is the point of the lens through which a wearer is configured to gaze in a main gaze direction when wearing the lens when being mounted in said frame. In a particular example, the wearer is wearing the lens in standard wearing conditions.

[0066] An optical power provided at least at the center point O.

[0067] In a particular embodiment, the lens comprises an optical function, more particularly a dioptric function. Said dioptric may be formed within a disk 18 having a radius R (shown in figures 5 and 6) over the rear face of the lens 1. The radius may be greater or equal to 15 mm and smaller or equal to 25 mm, preferably equal to 20 mm. Said disk may correspond to the intersection on the rear face 12 of a cone of vision having a generatrix being the main gaze direction. Said cone having for example a cone aperture angle may be bigger or equal to 30°, lower or equal to 50°, preferably equal 40°.

[0068] The method comprises a portion of the contour determining step S2. During said step, a portion of the contour Cpi, P2 (illustrated in figure 4), delimited by the extremities Pl, P2 of the contour of the initial lens 1 is determined. This portion of the contour Cpi, P2 corresponds to the portion of the contour of the initial lens 1 to be modified.

[0069] In a particular embodiment, the portion of the contour Cpi, P2 may be formed on the temporal portion 14. In an alternative embodiment, the portion of the contour Cpi, P2 may be formed on the nasal portion 16.

[0070] Further, figure 4 illustrates a cylindrical referential (Q, 0) centered in O and having an angle 9 = 0° along the axis X, towards the nose of the wearer, Q defines a radial distance while in said cylindrical referential, the coordinates of the points Pl and P2 are defined as (QI, 9i) and (Q2, 02).

[0071] The method comprises a constraint determining step S3. During said step, a constraint is determined over the portion of the contour Cpi, P2.. Said constraint can be a thickness or a width constraint. [0072] The thickness constraint defined by a thickness profile T(0), as illustrated in figure 8. The thickness profile T(0) associates a required thickness constraint T(0i) at any point Pi (Qi, 0i) of the portion of the contour CPI,P2 between the extremities Pl, P2. At least one point of the portion of the contour CPI,P2 has a thickness constraint different of the thickness of the initial lens in said point.

[0073] The thickness constraint in points Pl, P2 is fixed and is defined by T(0i) and T(02), is equal to the thickness of the initial lens in points Pl, P2. Or

[0074] The width constraint defined by a width profile W(0), as illustrated in figure 9. The width profile W(0) associates a required width constraint W(0i) at any point Pi.

[0075] W(0i) defines a distance separating Pi (Qi,0i) of the portion of the contour CPI,P2 and

Pi’ ( i’,0i), along the axis Opi, with P< i. Said distance defines, for a partiicular angle 0i, the distance starting from Pi in direction of O over which the initial lens canbe modified. Pi’ may also be defined as Qstart and Qi may be defined as Qmax (defining a point over the portion of the contour CPI,P2). It is to be noted that Qstart varries for each 0i.

[0076] A fixed constraint is defined by W(0i) and W(02) is equal to 0mm.

[0077] For each Pi ’ (Qi ’ ,0i), the thickness in the point Pi’ corresponds to the thickness of the initial lens in said point. Advantageously, this enables to have a continuity between the modified and non modified portions of the final lens.

[0078] In step S3, when the determined constraint is the thickness constraint, the variation law TV(0) is a width profile derived from the thickness profile T(0) and a curvature variation law CO(Q). When the determined constraint is the width constraint, the variation law TV(0) is a thickness profile derived from the width profile W(0) and a curvature variation law CO(Q). This ensures that the adaptation of the lens thickness and width profiles is harmonized to meet the specified constraints. By linking thickness constraints to width adjustments and vice versa, the method allows precise control over lens modifications. This for example, ensures that the peripheral portions of the lens are tailored to meet specific requirements without altering the central optical zone. For example, a thickness constraint might ensure the lens fits properly into the frame without adding bulk. For example, a width constraint might ensure a smooth transition of lens curvature, preventing sharp edges or discontinuities. For example, adapting thickness indirectly through width changes enables smoother transitions in lens geometry, eliminating visible or abrupt changes that might be considered unesthetic. This is particularly relevant for myopic and hyperopic lenses, where thickness variations are more pronounced. Advantageously, the ability to play with thickness and width based on constraints makes this method highly adaptable to various wearer prescriptions, frame designs, and sensitivities. This leads to personalized solutions, improving wearer satisfaction, and ensures that wearers benefit from the desired optical correction without experiencing distortions or visual discomfort. In essence, this interplay between thickness and width constraints provides a practical and effective way to address challenges in ophthalmic lens design, ensuring aesthetic, mechanical, and optical excellence.

[0079] The determined constraint of step S3 can be derived in a several manners:

• data coming from one or more wearer test; and/or

• a test done in shop to evaluate wearer sensitivity to distortion; and/or

• wearer and frame data (Rx, centration, frame size.) of the eyewear equipment; and/or

• mounting parameters of the eyewear equipment.

[0080] The method comprises a variation law determining step S4. The variation law TV(0) is determined at least based on the determined constraint.

[0081] In the embodiment, where the determined constraint is a thickness constraint determined by the thickness profile T(0), the variation law TV(0) corresponds to a width profile.

[0082] In the embodiment, where the determined constraint is a width constraint determined by the width profile W(0), the variation law TV(0) corresponds to a thickness profile.

[0083] The method comprises a target zone determination step S5. During said step, the target zone 20 (illustrated in figure 7) of the initial lens to be modified is determined. The target zone is defined in the cylindrical referential (Q, 0). Then said target zone is projected, according to the direction normal to the point O, on the rear face of the initial lens.

[0084] Said target zone is delimited by the contour CPI,P2 and the width profile, when the determined constraint in the step S3 is the width constraint. [0085] Alternatively, said target zone is delimited by the portion of the contour CPI,P2 and variation law TV(0), when the determined constraint in step S3 is the thickness constraint.

[0086] The method comprises a modification step S6, wherein the initial lens is modified over the target zone, so as to fulfill the determined constraint. For any of the point Pi of the portion of the contour Cpi,p2. Additionally, following the modification step S6, the profile of the variation law TV(0), being a thickness or a width profile, is fulfilled for any of the point Pi of the portion of the contour Cpi,p2.

[0087] Finally, the method comprises a final lens providing step S7, wherein a final lens is provided. Said final lens is the lens resulting from the modification step S6, namely, the initial lens being modified over the target area.

[0088] Figure 10 shows a variation of the thickness, along an angular direction, between the initial and the final lens for myopic wearer. It can be noted a thickness reduction over the temporal side of the final lens.

[0089] Figure 11 shows a variation of the thickness, along an angular direction, between the initial and the final lens for hyperopic wearer. It can be noted a thickness increase over the temporal side of the final lens.

[0090] The rear face 12 of the final lens is continuous surface, continuously derivable, where altitude variation is monotonous along any direction.

[0091] The definition of the variation law will be further detailed hereafter.

[0092] When the determined constraint according to step S3 is the width constraint defined by a width profile W(0), the variation law TV(0) is a thickness profile derived from:

• the width profile W(0), and

• a curvature variation law Ce(g).

[0093] Figure 12 illustrate the curvature variation law Ce(g). Said figure illustrates the variation of the curvature at an angle 0i, between the center point O and the point Pi of the contour of the rear face 12 of the lens 1.

[0094] The curvature variation law Cei(p) comprises two fixed constraints;

• the final curvature COi(pi) at the point Pi of the portion of the contour CPI,P2, and

• the minimum curvature value minCei(Q). [0095] Further, the curvature variation law can be defined by the following equation:

[0096] Wherein Z(p) defines the altitude of any point of rear face 12 according to the angle 0:

Z0(p) = Z(p — dp) + dZ(p — dp) + C0(p — dp)

[0097] Thanks to this equation, the altitude of the surface can be expressed with slope (first radial derivative) and curvature (linked to second radial derivative) constraints.

[0098] When, for an angle 0i, p is inferior as p_start, the curvature of the final lens is identical to the one of the initial lens, 0i being an angular direction within the portion of the contour Cpi,P2.

[0099] And when p is between _start and _max, corresponding to the distance W(0i), the curvature can slowly be modified, to reach a curvature constraint. The curvature constraint can be maintained till the slope (dZ/d p) reaches a given value. On the final part, close to _max, the curvature can be set to a specific value. For example, said specific value is equal to zero.

[00100] It is known that current machining tool, in the domain of optical lens, can achieved a minimum curvature radius variation over the lens. Based on the length of the distance W(0), it can be acknowledged the possible varition of the altitude consequently it can be derived the the altitue Ze(p_max) over the point Pi within the portion of the contour Cpi,p2. From said altitude at the point Pi, it can be derived a modified thickness in said point. Form the difference between the thickness of the initial lens and the modified thickness at the point Pi, the value of the variation TV(0i).

[00101] By proceeding accordingly, for every angular direction comprised within the portion of the contour CPI,P2, the variation of the thickness over the portion of the contour CPI,P2, the variation law TV(0), being a thickness profile, can be derived. [00102] When the determined constraint according to step S3 is the thickness constraint defined by a thickness profile T(9), the variation law TV(0) is a width profile derived from:

• the thickness profile T(9), and

• a curvature variation law C9(Q).

[00103] Said width profile TV(0) associates a required width constraint TV(9i) at any point Pi of the portion of the contour Cpi,p2. TV(0i) is a distance separating Pi (Qi, 0i) and Pi’ ( i’, 0i), along the axis OPi, with Qi’ < Qi.

[00104] After having defined the relationship between a width profile and the thickness profile thanks to the curvature variation law CO(Q). The relationship can be derived when the thickness is provided as an input as the determined constraint.

[00105] When the thickness constrained T(0i) is known at a point Pi of the portion of the contour CPI,P2, the variation of the thickness at said point Pi with respect to the initial lens can be derived.

[00106] As described earlier, the curvature variation law CO(Q) defines the variation of the altitude over the rear face of a lens between the point O and Pi for and angle 0i. Said curvature variation having a minimum curvature radius minimum, defined hereby by the constraint curvature value minCei(Q).

[00107] From said curvature variation law Cei(Q) and minimum curvature radius minCurv, a maximal variation rate of the curvature can be derived. From said maximal variation rate of the curvature, it can be determined, for said angle 0i, the minimum distance over the axis PiO to enable that the constrained thickness at the point Pi and to provide the thickness of the initial lens at a location Pi’ (Qi’, 0i), with Qi’ < Qi.

[00108] Accordingly, from the thickness profile T(0i) and the curvature variation law Cei(Q), it can be determined the width profile TV(0i) at the point Pi.

[00109] By proceeding accordingly, for every angular direction comprised within the portion of the contour CPI,P2, the variation of the width for every angular direction within the portion of the contour CPI,P2, the variation law TV(0) being a width profile can be derived.

[00110] The curvature variation law CO(Q) is continuous along the angular direction 9. [00111] The curvature variation law Ce(g) satisfies the following constraints:

• at the point Pi of the portion of the contour CPI,P2, Cei(Qmax) being defined as an input, and

• for any point between O and Pi’, the curvature Cei(g) is equal to the curvature of the initial lens in said point, such that the thickness of the final lens remains unchanged over the distance OPi’.

[00112] When the determined constraint according to step S3 is the thickness constraint defined by a thickness profile T(9), the target zone 20 is delimited on one hand by the portion of the contour CPI,P2 and on the other hand by the width profile TV(0) defined above.

[00113] Figure 13 illustrates the variation of the curvature profile between O and a point Pi of the portion of the contour CPI,P2, along the angular direcrtion 9i. Cei(g) depends on the first and second derivates of the function Z(Q). The curvature varies between Qstart and Qmax. As described above Qstart differs for each angular direction 0i comprised within the portion of the contour Cpi,p2.

[00114] Over the distance [O, Qstart], no curvature variation occurs, as over said distance, the curvature is identical to the curvature of the initial lens 1.

[00115] In a particular embodiment, the rate of curvature variation is preserved over a distance [Qstart, Qa], reaching the minimum curvature radius in Q_a. Then the curvature remains constant over a distance [Q_a, Qb]. The rate of curvature variation is preserved over a distance [Qb, Qc] until reaching in Q_C the final curvature radius. Then the curvature remains constant over a distance [Q_C, Qmax] so as to provide the desired curvature at the location of the point Pi of within the portion of the contour Cpi,p2.

[00116] In a particular embodiment, the target zone 20 is a subzone of a zone delimited on one hand by the portion of the contour CPI,P2, and on the other hand by the width profile W(9) or the width profile formed by the variation law TV(0), void of the surface of the disk 18 centered in O and having a radius R (shown in figures 5 and 6) intersecting said delimited zone.

[00117] In a particular, the target zone 20 is a subzone of a zone delimited on one hand by the portion of the contour CPI,P2, and on the other hand by the width profile W(9) or the width profile formed by the variation law TV(0). Said width profile W(9) or TV(9) having a profile not intersecting the disk 18. [00118] More particularly, figure 6 illustrates a particular embodiment, wherein for any point Pi of the portion of the contour CPI,P2, the width defined according to W(0i) or TV(0i), defining an ideal width Wideai over which the initial lens according to the angular direction 0i. However, said segment Wideai intersect the disk 18 of radius R centered in O.

[00119] As it is desired to not modify the lens within said disk 18, the initial lens cannot be modified within said disk 18. Then, there is a need to adapt the width for said angular direction 0i, from Pi until reaching the disk over the axis OPi. This adapted width corresponds to Wiimit.

[00120] Alternatively Wiimit can be determined in a fixed manner, smaller or equal tolO mm, biger or equal to 7 mm.

[00121] Advantageously, a central portion of the lens remains unchanged and the optical function (for example a dioptric function) within said central portion is not altered when modifying the initial lens.

[00122] The radius R may depend on the sensibility of the wearer. For example, this sensitivity can be determined following a test performed by a eye care professional.

[00123] The radius R may depend on the wearer’s prescription, including sphere and/or cylinder and/or axis and/or addition.

[00124] The radius R may depend on generic data such as standard wearing condition and/or eyewear equipment frame data and/or data relative to the centration of the lens within the frame.

[00125] The method according to the disclosure may further comprise an optional thickness optimizing step S8. Said thickness optimizing step S8 occurs after modification step S6 and before final the lens providing step S7.

[00126] In said thickness optimizing step S8, for any point N of the rear face of the modified initial lens according to step S6, a thickness, being the distance between said point N and its projection N’ on the front face according to a direction defined by the axis normal to the rear face in O can be obtained. This enables to determine the local thickness of the modified lens 1 at the position of the point N of over the rear face 12 of the modified lens 1.

[00127] Proceeding accordingly for any point of the rear face, it can be determined the minimum thickness TN of the modified initial lens according to step S6 of the method. [00128] If the minimum thickness TN of the final lens is superior to a thickness threshold Tth, the thickness optimizing step S8 leads to an offset of the rear face relative to the front face in the projection direction, defined by the axis normal to the rear face in O, by the amount of the difference of the minimum thickness of the modified initial lens according to step S6 TN minus the thickness threshold Tth. The final lens following the optimization is then provided in final the lens providing step S7.

[00129] Advantageously, this enables to reduce the overall thickness of the lens and reduce the amount of material necessary to manufacture this final lens to be provided in step S7.

[00130] The following part of the disclosure is directed to exemplary embodiments.

Example 1: Myopic wearer and the determined constraint being a width profile

[00131] In the present first example, the wearer as a prescription, wherein the sphere is of - 3.25 D and the cylinder of -0.5 D over an axis of 15°. The centration parameter being a right and/or left half pupillary distance PD = 31.5 mm and a fitting height FH = 33mm. The fitting height is a vertical distance from the optical center O or fitting cross to the bottom of the frame contour. The bottom of the frame is defined for the angle 0 = 270° in the cylindrical referential (Q, 9). The frame of the eyewear to be considered is Ray-ban Aviator ® having a lens total width of 62 mm.

[00132] Figure 37 illustrates a representation of the contour of an ophthalmic lens 1, before (circular shape) and after (designed by the reference 1) cutting out. The lens 1, after cutting out, has a contour of a template of the frame. This cutting out of the lens allows the subsequent fitting of the lens in the frame.

[00133] Figure 37 shows the lens total width A of the template, according to a horizontal axis determining the distance between the farthest temporal and nasal end. Figure 37 also illustrate a distance being the total lens height B, according to a vertical axis between, the highest and lowest ends of the lens 1. The fitting cross or the optical center may be located as the position corresponding to the half of the total lens width A/2 and the half of the total lens height B/2. [00134] The profile of width over the angle 0 = 90° to 9 = 270° of the cylindrical referential, as illustrated in figure 14.

[00135] The portion of the contour CPI,P2 is defined over the angular sector 0i = 90° to 02 = 270°. Advantageoulsy, the initial lens will only modified over the temporal side.

[00136] For a point Pi of the portion of the contour CPI,P2, corresponding to the angular direction 0i= 181°, W(0i) = 7.2 mm. The point Pi’(Q_start, 0i) spaced from Pi in direction of O by 7.2 mm is space from O by 27.25 mm Then, Q_start= 27.25 mm. This spacing from O is compliant with a disk 18 centered in O having a radius of 25 mm over which it is desired to not modify the structure of the initial lens 1. 0i= 181° corresponding to the centring poistion of the temple.

[00137] The combination of the width profile and the portion of the contour CPI,P2 define the target zone 20 to be modified of the initial lens.

[00138] Further, a curvature variation law illustrated in figure 15 is defined. Said curvature variation law comprises the following constraint:

• the minimum curvature radius minCurv = -14 mm,

• the final curvature radius finCurv = 100 mm,

• the following distance over the angular direction: o [Qstart, Qa] = 3.43 mm, o [Q_a, Qb] = 0.68 mm, and o [Qb, Qc] = 2.75 mm.

[00139] As described above, based on the width profile as determined constraint of step S3 of the method, it is possible to derive the altitude Z ( , 9) for any point of the target zone and to detemine a variation law TV(0) defining a thickness profile over the portion of the contour CPI,P2, as illustrated in figure 16. Advantageously, the modification of the initial lens in step S6 of the method enables to reduce the thickness of the initial lens over the portion of the contour Cpi,p2, up to 1.4 mm, for the angular direction 0i = 181°.

[00140] Further, figure 17 illustrates the thickness of the the initial and the modified lens over the whole contour. It is noticed for any point of the contour outside of the portion of the contour CPI,P2, the thickness is identical to the initial lens and within said portion of the contour CPI,P2, the thickness of the lens has reduced as shown by the arrow. [00141] Figure 18 illustrates the varaition of the altitude Z along the angular direction 0i = 181°, between O and Pi. It can be noticed a variation of the altitude over the distance W(0i)=7.2 mm, wherein at the point Pi of the final lens, the alituted has reduced of 1.4 mm with respect to the initial lens as shown by the arrow.

Example 2: Hyperopic wearer and the determined constraint being a width profile

[00142] In the present first example, the wearer as a prescription, wherein the sphere is of 4.5 D and the cylinder of 0 D over an axis of 0°. The centration parameter being a right and/or left half pupillary distance PD = 31 mm and a fitting height FH = 34mm. The fitting height is a vertical distance from the optical center O or fitting cross to the bottom of the frame contour. The bottom of the frame is defined for the angle 0 = 270° in the cylindrical referential (Q, 0). The frame of the eyewear to be considered is Ray-ban Aviator ® having a lens total width A of 58 mm.

[00143] The profile of width over the angle 0 = 90° to 0 = 270° of the cylindrical referential, asd illustrated in figure 19.

[00144] The portion of the portion of the contour CPI,P2 is defined over the angular sector 0i = 90° to 02 = 270°. Advantageoulsy, the initial lens will only modified over the temporal side.

[00145] For a point Pi of the portion of the contour CPI,P2, corresponding to the angular direction 0i = 190°, W(0i) = 7.2 mm. The point Pi’(Q_start, 0i) spaced from Pi in direction of O by 7.2 mm is space from O by 27.6 mm Then, Q_start= 27.6 mm. This spacing from O is compliant with a disk 18 centered in O having a radius of 25 mm over which it is desired to not modifiy the structure of the initial lens 1.

[00146] The combination of the width profile and the portion of the contour CPI,P2 define the target zone 20 to be modified of the initial lens.

[00147] Further, a curvature variation law illustrated in figure 20 is defined. Said curvature variation law comprises the following constraint:

• the minimum curvature radius minCurv =+14 mm,

• the final curvature radius finCurv = 100 mm,

• the following distance over the angular direction: o [Qstart, Qa] = 3.43 mm, o [Q_a, Qb] = 0.68 mm wherein a curve constrtraint Curv_COnstraint is applied, and o [Qb, Qc] = 2.75 mm.

[00148] As described above, based on the width profile as determined constraint of step S3 of the method, it is possible to derive the altitude Z (Q, 9) for any point of the target zone and to detemine a variation law TV(0) defining a thickness profile over the portion of the contour Cpi,p2, as illustrated in figure 21. The modification of the initial lens in step S6 of the method result in an increase of the thickness of the initial lens over the portion of the contour CPI,P2, up to 0.9 mm in the direction 0i = 190°.

[00149] Further, figure 22 illustrates the thickness of the the initial and the modified lens over the whole contour according to the modifying step S6. It is noticed for any point of the contour outside of the portion of the contour CPI,P2, the thickness is identical to the initial lens and within said portion of the contour CPI,P2, the thickness of the lens has increased as shown by the arrow.

[00150] When considering figure 22, it is be noted that the thickness over the whole contour of the lens is above a thickness threshold of Tth of 1 mm, as the minimal thickness of the modified lens, following the increase of the thickness over the temporal portion, is about 1.7 mm.

[00151] Following the optimization, according to thickness optimizing step S8, the overall thickness of the modified lens in the modifying step S6, can be further reduced as illustrated in figure 23, as shown by the arrows.

[00152] Said overall thickness reduction enables to reduce the thickness over the nose portion over at least 0.8 mm, mor particularly for 9= 340°.

Example 3: Myopic wearer and the determined constraint being a thickness profile

[00153] In the present first example, the wearer as a prescription, wherein the sphere is of - 5 D and the cylinder of 0 D over an axis of 0°. The centration parameter being a right and/or left half pupillary distance PD = 31 mm and a fitting height FH = 34mm. The fitting height is a vertical distance from the optical center O or fitting cross to the bottom of the frame contour. The bottom of the frame is defined for the angle 9 = 270° in the cylindrical referential (Q, 9). The 1 frame of the eyewear to be considered is Ray-ban Aviator ® having a lens total width A of 58 mm.

[00154] The profile of thickness over the angle 0 = 90° to 9 = 270° of the cylindrical referential., as illustrated in figure 25.

[00155] The portion of the portion of the contour CPI,P2 is defined over the angular sector 0i = 90° to 02 = 270°. Advantageoulsy, the initial lens will only modified over the temporal side.

[00156] For a point Pi of the portion of the contour CPI,P2, corresponding to the angular direction 0i = 190°, the thickness of the initial lens is 7.3 mm and the the desired thicknes constraint T(0i) in said point Pi is a reduction of 2.5 mm. Advantageously, the modification of the initial lens in step S6 of the method enables to reduce the thickness of the initial lens over the portion of the contour Cpi,p2. . 0i= 190° corresponding to the centring poistion of the temple.

[00157]

[00158] Further, a curvature variation law illustrated in figure 24 is defined. Said curvature variation law comprises the following constraint for the angular direction 0i= 190°:

• the minimum curvature radius minCurv = 14 mm,

• the final curvature radius finCurv = 100 mm,

• the following distance over the angular direction: o [Qstart, Qa] = 2.84 mm, o [Q_a, Qb] = 0.58 mm, and o [Qb, Qc] = 2.72 mm.

[00159] As described above, it has been the define how to define a variation law TV(0), being a widtwh profiled, based on the thickness profile T(9) as determined constraint according to step S3 and the curvature variation law CO( ). The distance between O and Pi is smax(0i) = 34.3 mm and the derived width TV(0i) = 9.57 mm. Consequently, Qstart(0i) = 25.1 mm.

[00160] Form each angle direction 9 of the portion of the contour CPI,P2, it can be obtained the correction variation law value TV(0), so as to define the with profile, as illustrated in figure 26.

[00161] Further, figure 27 illustrates the thickness of the the initial and the modified lens over the whole contour. It is noticed for any point of the contour outside of the portion of the contour CPI,P2, the thickness is identical to the initial lens and within said portion of the contour CPI,P2, the thickness of the lens has reduced over TV(as shown by the arrow.

[00162] Figure 28 illustrates the varaition of the altitude Z along the angular direction 0i = 190°, between O and Pi. It can be noticed a variation of the altitude over the distance TV(0i) = 9.57 mm, between the initial lens and the fianal lens, being a reduction of altittude (as shown by the arrow).

[00163] In an exemplary embodiment, the maximal width W according to a particular

angular direction 0i, for a point Pi of of the portion of the contour CPI,P2, is depending on the sensitivity of the wearer. The wearer sensitivity can be defined as a score level. Said score level can be defined by an eyecare practitioner or in an eyewear shop. The score level can be derived from measurement or an evaluation.

[00164] According to an example, illustrated in figure 29, the evolution of the maximal width Wi.imit(0i) is evolving in a non-linear as shown by the line comprising rounds bullets. For a medium score level of wearer sensitivity, the maximal width WLimit(Oi) is equal to 7 mm and varying to +/-50% at extremum for a score a score level of wearer sensitivity of 0 or 10. For a score level of wearer sensitivity of 0, the maximal width WLimit(Oi) is equal to 10.5 mm, whereas for a score level of wearer sensitivity of 10, the maximal width Wi.imit(0i) is equal to 3.5 mm

[00165] In another exemplary embodiment, the maximal width is depending on

the ideal width Wideai(0i) for the angular direction 0i and the disk centered on the center optic O. The disk defines the zone of the lens to be preserved. The initial lens is not modified within said disk. The disk results from the intersection of a cone of vision over the rear face. Said cone can have aperture angle of 40° or 50°. In this particle example, three couples of ideal widths Wideai(Oi) and aperture angles are defined:

• Couple 1 : o Wideai(Oi) = 7 mm, and o Aperture angle 50°;

• Couple 2: o Wideai(0i) = 7 mm, and o Aperture angle 40°;

• Couple 3 : o Wideai(0i) = 10 mm, and o Aperture angle 40°.

[00166] The maximal width W is defined based on the combination of both criterion

with a priority given to the size of the disk, depending on the angle of aperture of the cone.

[00167] The ideal width Wideai(9i) and/or the angle of the cone aperture can be defined according to a graphic as illustrated in figure 30. It can be noticed that as the score level of wearer sensitivity increases, the ideal width Wideai(9i) continuously reduces from 14 mm to 7 mm, whereas, the angle of aperture of the cone increases from 40° (corresponding to a disked centered in O having a radius of 20 mm) up to 50°.

[00168] This dimension of the disk can restrain the maximal width Wi.imit(9i), more particularly for the angular direction 0i = 180°, corresponding to the half of the lens total height B/2 in the temporal zone. Figure 31 discloses a disk of a radius of 20 mm. The maximal width Wi.imit(9i) is equal to 7 mm (as shown by the distance PG). Said maximal width Wi.imit(9i) may be lower than the ideal width Wideai(9i).

[00169] Alternatively, the width personalization may depend on frame and/or wearer data.

[00170] Depending on the size of the frame and the lens centration into the frame, the width can be adapted. The furthest the lens contour, on the temporal sided, is from the pupil, the larger the width can be.

[00171] As for an example, a given wearer is myope and has a prescription of a sphere of - 4D , a pupillary distance of 32mm, fitting height at the half of the lens total height B/2. The wearer is wearing the eyewear equipment in standard wearing conditions. In the present example two eyewear equipment are considered having each different frame data. The first eyewear equipment has a lens having a lens total width A of 55 mm and a lens total height B of 40 mm. The second eyewear equipment has a lens having a lens total width A of 65 mm and a lens total height B of 40 mm. P55 is the point of the portion of the contour CPI,P2, for 9 = 180° for the first eyewear equipment and Pes is the point of the portion of the contour CPI,P2, for 9 = 180° for the second eyewear equipment. The angle direction 9 = 180° corresponds to B/2 in the temporal zone.

[00172] For both, the first and the second eyewear equipment, the preserve aera corresponds to a disk of a radius of 20 mm centered in O, as illustrated in figure 32. [00173] Figure 33 illustrates the impact of the pupilar distance PD and the total width A (abscissa) over the dimension of the width. The curve having round bullets corresponds to a pupillary distance of 35 mm. The curve having squares corresponds to a pupillary distance of 32 mm. The curve having triangles corresponds to a pupillary distance of 29 mm. It can be noted that as the total width A increases, the width increases linearly. Further, it can be noted that as the pupillary distance reduces, higher the width is.

[00174] According to another exemplary embodiment, the width can be defined as a function of the total width A and being limited by a minimum threshold and a maximum threshold. These thresholds allow a better acceptance of the wearer to a large width W(0i). A minimum distance is necessary to be able to manage a thickness variation over the target area according to the present disclosure.

[00175] Figure 34, alike figure 33, illustrates the impact of the pupilar distance PD and the total width A (abscissa) over the dimension of the width. The curve having round bullets corresponds to a pupillary distance of 35 mm. The curve having squares corresponds to a pupillary distance of 32 mm. The curve having triangles corresponds to a pupillary distance of 29 mm. It can be noted that as the total width A increases, the width increases. For the curve corresponding to a pupillary distance of 35 mm, it can be seen a minimum width of 5 mm. For the curve corresponding to a pupillary distance of 29 mm, the variation of the width is no longer linear when approaching the upper threshold so as to not exceed the maximum threshold of 15 mm.

[00176] The minim and maximum threshold enable to achieve a compromise between limiting the proportion of the lens being altered by the modification while ensuring that the target zone to be modified is sufficient to enable a noticeable thickness variation over the final lens according to the disclosure.

[00177] According to another exemplary embodiment, the radius of the disk centered on the optical center O, defining the zone of the lens to be preserved from any modification, is depending on the total width A.

[00178] Figure 35 illustrates the impact of the pupilar distance PD and the total width A (abscissa) over the radius of the disk. The curve having round bullets corresponds to a pupillary distance of 35 mm. The curve having squares corresponds to a pupillary distance of 32 mm. The curve having triangles corresponds to a pupillary distance of 29 mm. It can be noted that as the total width A increases, the radius increases. Further, it can be noted that as the pupillary distance reduces, higher the radius is.

[00179] According to another exemplary embodiment, the maximal width Wi imitfOi) may be defined according to the prescription of the wearer. It is known that the prismatic deviation changes based on the prescription of the wearer. When gazing at an object, the lowering of the gazing direction is different between a myope and hyperope wearer. As a result, the radius of the disk of the zone to be preserved may be function of the ametropia degree of the wearer.

[00180] Figure 36 illustrates the variation of the angle of the cone aperture (resulting in a variation of the radius of the disk defining the zone to be preserved on the lens) based on the mean sphere prescription of the wearer. It is noticeable, that the cone aperture angle may remain identical if the mean sphere is lower than -6 D (the cone aperture angle is of 30°) or higher than 6 D (the cone aperture angle is of 40°), whereas said cone aperture angle variates as the mean sphere evolves from -6 D to 6 D.

[00181] The disclosure has been described above with the aid of embodiments without limitation of the general inventive concept.

[00182] Many further modifications and variations will suggest themselves to those skilled in the art upon making reference to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the disclosure, that being determined solely by the appended claims.

[00183] In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used. Any reference signs in the claims should not be construed as limiting the scope of the disclosure.

Claims

1. Method for adapting thickness of an initial lens (1), the method comprising:

• an initial lens data obtaining step SI, wherein the initial lens data comprises: o a contour of the lens configured to be mounted in a frame, o a shape of the front face (10), o a shape of the rear face (12), o positioning of the front face relative to the rear face, o a position of a center point O on the rear face of the lens, being the point of the lens through which a wearer is configured to gaze in a main gaze direction when wearing the lens when being mounted in said frame, and o an optical power provided at least at the center point O,

• a portion of the contour determining step S2, wherein a portion of the contour CPI,P2 of the initial lens to be modified is determined, said portion of the contour having two extremities Pl, P2, said contour portion CPI,P2 being defined in a cylindrical referential (Q, 9) centered in O, where Pl coordinates are (QI, 0i) and P2 coordinates are (Q2, 02),

• a constraint determining step S3, wherein said determined constraint is: o a thickness constraint defined by a thickness profile T(0), wherein said thickness profile T(0) associates a required thickness constraint T(0i) at any point Pi (Qi, 0i) of the portion of the contour CPI,P2 between the extremities Pl, P2 wherein the thickness constraint in points Pl, P2, T(0i) and T(02) is equal to the thickness of the initial lens in points Pl, P2. or o a width constraint defined by a width profile W(0), wherein said width profile W(0) associates a required width constraint W(0i) at any point Pi, wherein W(0i) is a distance separating Pi (Qi,0i) and Pi’ (Qi’,0i), with P< Qi, wherein W(0i) and W(0i) is equal to 0,

• a target zone determination step S5, wherein a target zone (20) of the initial lens is determined based on the determined constraint of step S3 or on the variation law TV(0),

• a modification step S6, wherein the initial lens is modified over the target zone, so as to fulfill the determined constraint and the variation law TV(0) for any of the point Pi, and a final lens providing step S7, wherein a final lens being the lens resulting from step S6.

2. Method according to claim 1, wherein the target zone is projected on the rear face of the initial lens.

3. Method according to claim 1 or 2, wherein the determined constraint according to step S3 is the width constraint defined by a width profile W(0), and wherein the variation law TV(0) is a thickness profile derived from:

• the width profile W(0), and

• a curvature variation law Ce(g).

4. Method according to claim 3, wherein the target zone is delimited on one hand by the portion of the contour CPI,P2 and on the other hand by the width profile W(0).

5. Method according to claim 1 or 2, wherein the determined constraint according to step S3 is the thickness constraint defined by a thickness profile T(0), and wherein the variation law TV(0) is a width profile derived from:

• the thickness profile T(0), and

• a curvature variation law CO(Q). wherein said width profile TV(0) associates a required width constraint TV(0i) at any point Pi, wherein TV(0i) is a distance separating Pi (Qi, 0i) and Pi’ ( i’, 0i), with Qi’ < Qi.

6. Method according to claim 5, wherein the target zone is delimited on one hand by the portion of the contour CPI,P2 and on the other hand by the width profile TV(0).

7. Method according to claim 3 or 5, wherein the target zone is a subzone of a zone delimited on one hand by the portion of the contour CPI,P2, and on the other hand by the width profile W(0) or the width profile formed by the variation law TV(0), void of the surface of a disk (18) centered in O and having a radius R intersecting said delimited zone.

8. Method according claim 7, wherein the radius R depends on the sensibility of the wearer.

9. Method according claim 7 or 8, wherein the radius R depends on the prescription of the wearer.

10. Method according to any of claims 7 to 9, wherein the radius R is set in a fixed manner.

11. Method according to any claims 3 to 10, wherein the curvature variation law Ce(g) is continuous.

12. Method according to any of claims 3 to 11, wherein for each point Pi’ (Qi’, 0i) obtained from:

• the with profile W(0i), relative to the point Pi ( i, 0i), or

• the variation law TV(0i), when the determined constraint is the thickness constraint, Cei(Qi’) is equal to the curvature Cei(Qi’) of the initial lens in said point Pi’.

13. Method according to any of claim 3 to 12, wherein the curvature variation law Cei(Q) is defined based on two criterions:

• the final curvature Coi(Qi) at the point Pi, and

• the minimum curvature value minCoi(Q).

14. Method according to any of the preceding claims, wherein for any point N of the rear face of the modified initial lens according to step S6, a thickness, being the distance between said point N and its projection N’ on the front face according to a direction defined by the axis normal to the rear face in O, determining the minimum thickness TN of the modified initial lens, if the minimum thickness TN of the final lens is superior to a thickness threshold Tth, the method further comprises, after modification step S6 and before the lens providing step S7,a thickness optimizing step S8 being the offset of the rear face relative to the front face in the projection direction by the amount of the difference of the minimum thickness of the modified initial lens according to step S6 TN minus the thickness threshold Tth.