CA2135229A1 - Contact lens for correction of presbyopia - Google Patents
Contact lens for correction of presbyopiaInfo
- Publication number
- CA2135229A1 CA2135229A1 CA 2135229 CA2135229A CA2135229A1 CA 2135229 A1 CA2135229 A1 CA 2135229A1 CA 2135229 CA2135229 CA 2135229 CA 2135229 A CA2135229 A CA 2135229A CA 2135229 A1 CA2135229 A1 CA 2135229A1
- Authority
- CA
- Canada
- Prior art keywords
- lens
- correction
- vision
- present
- presbyopia
- Prior art date
- Legal status (The legal status 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 status listed.)
- Abandoned
Links
- 201000010041 presbyopia Diseases 0.000 title claims abstract description 18
- 230000004438 eyesight Effects 0.000 claims abstract description 32
- 208000001491 myopia Diseases 0.000 claims abstract description 16
- 230000002093 peripheral effect Effects 0.000 claims description 2
- 241000219739 Lens Species 0.000 description 52
- 210000001508 eye Anatomy 0.000 description 22
- 239000000463 material Substances 0.000 description 7
- 102100025172 Calpain-1 catalytic subunit Human genes 0.000 description 5
- 101710124171 Calpain-1 catalytic subunit Proteins 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 230000004379 myopia Effects 0.000 description 5
- 210000001747 pupil Anatomy 0.000 description 5
- 238000005266 casting Methods 0.000 description 3
- 210000001525 retina Anatomy 0.000 description 3
- 230000004304 visual acuity Effects 0.000 description 3
- 208000029091 Refraction disease Diseases 0.000 description 2
- 206010047513 Vision blurred Diseases 0.000 description 2
- 230000004430 ametropia Effects 0.000 description 2
- 210000005252 bulbus oculi Anatomy 0.000 description 2
- 210000004240 ciliary body Anatomy 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 208000014733 refractive error Diseases 0.000 description 2
- LLLWMXQKXWIRDZ-UHFFFAOYSA-N 1-ethenylpyrrolidin-2-one Chemical compound C=CN1CCCC1=O.C=CN1CCCC1=O LLLWMXQKXWIRDZ-UHFFFAOYSA-N 0.000 description 1
- 102100026735 Coagulation factor VIII Human genes 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- 101000911390 Homo sapiens Coagulation factor VIII Proteins 0.000 description 1
- WOBHKFSMXKNTIM-UHFFFAOYSA-N Hydroxyethyl methacrylate Chemical compound CC(=C)C(=O)OCCO WOBHKFSMXKNTIM-UHFFFAOYSA-N 0.000 description 1
- 208000004350 Strabismus Diseases 0.000 description 1
- 230000004397 blinking Effects 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004297 night vision Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000007779 soft material Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
- G02C7/00—Optical parts
- G02C7/02—Lenses; Lens systems ; Methods of designing lenses
- G02C7/04—Contact lenses for the eyes
- G02C7/041—Contact lenses for the eyes bifocal; multifocal
- G02C7/044—Annular configuration, e.g. pupil tuned
-
- G—PHYSICS
- G02—OPTICS
- G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
- G02C7/00—Optical parts
- G02C7/02—Lenses; Lens systems ; Methods of designing lenses
- G02C7/04—Contact lenses for the eyes
- G02C7/041—Contact lenses for the eyes bifocal; multifocal
- G02C7/042—Simultaneous type
Landscapes
- Health & Medical Sciences (AREA)
- Ophthalmology & Optometry (AREA)
- Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Eyeglasses (AREA)
Abstract
The present invention relates to a contact lens for correction of presbyopia comprising, in the central circular area, an aspherical lens for correction of near vision, and, in the annular periphery, a spherical single focus lens for correction of distance vision.
Description
213S22~
TITLE OF THE INVENTION
CONTACT LENS FOR CORRECTION OF PRESBYOPIA
BACKGROUND OF THE INVENTION
(a) Field of the Invention The present invention relates generally to a contact lens, and more specificallyto a hydrophilic, soft contact lens for correction of presbyopia, comprising in the circular center an aspherical lens area for near to intermediate vision, and, on its periphery, a spherical lens area for distance vision.
A person suffering from presbyopia is one whose ciliary body in the eye does not function at 100% level as age advances, in that the ciliary body does not adequately pull the lens of the eye to form a convex lens, resulting in blurred vision for objects at a near distance. Thelefore, a presbyopia patient needs corrective lenses that can provide normal vision for viewing distances of approximately 30 - 40 cm (13 - 16 inches).
Also, as a growing number of elderly people drive, they need adequate night vision for driving in the dark, as well as near distance vision for reading, regardless of the level the lumination. For this purpose, multifocal lenses have been developed, but they, or any other lenses for that matter, fall short of complete satisfaction.
If such multifocal lenses can provide correction for strabismus, ametropia or other astigm~ticm~, they will be much more useful.
- As used in the present specification and claims, the term, "multifocal lens", is defined as a lens having more than one focus depending on the position on the surface of the lens (usually a bifocal lens) which provides correction for far distance 213522~
or for reading, and capable of correcting the condition of presbyopia or plepre~byopic ametropia.
(b) Description of Prior Art Previously, bifocal contact lenses have been disclosed in, among others, the U.S.
patent Nos. 4199231 and 5125729.
The U.S. Patent No. 4199231 relates to a contact lens used for correction of presbyopia comprising on its rear face a spherical surface and on its front face an aspherical surface. Said invention pUI~ol ls to correct both near and distance visions, but has a drawback that the corrected vision, both for near and distance, is not clear.
Said invention also purports to minimi7e the blur circle, (a distorted image of near and distant objects formed on the retina when using a spherical lens), through using an aspherical lens, but the actual success rate is only about 50%, and diz7iness is frequently caused.
The U.S. Patent No. 5125729 relates to a multifocal lens comprising on its front face a central circular area having a spherical surface for distance vision, on its periphery, a surrounding annular area having an aspherical surface for near vision, and on yet a further outer periphery thereof, another surrounding annular area having a spherical lens for distance vision. Said invention has a drawback in that proper focus can be achieved only through adjusting the degree of lumination, since the correction area for distance vision is positioned in the central portion of the lens. To illustrate, the pupil of the eye dilates at night to cover much of the near vision area of the lens, thereby disturbing distance vision. Therefore, a potentially h~7~rdous situation may occur when driving or doing other activities at night that require distance vision.
Conversely, in a well lit area, the pupil contracts to cover only the distance vision area, thereby causing blurred vision for reading or other activities that require near vision.
213522g In addition, conventional bifocal lenses have been practically useless in cases where lens power is required for the near vision range, but not for the distance vision range (plano power).
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a contact lens for correction of presbyopia, without the existing drawbacks described above, that can provide near, intermediate and ~ nce vision regardless of whether in dark or well lit places. A
contact lens according to the present invention comprises a central circular area having an aspherical surface surrounded by an annular area having a spherical surface, and is capable of providing correction for near and intermediate vision as well as distance vlslon.
It is another purpose of the present invention to provide a mold casting method of producing the contact lens embodying the present invention that can produce aminute spherical surface with a high degree of accuracy, which has not beei~ possible with the conventional lathe-cutting method.
To achieve the above purposes, the contact lens of the present invention comprises a central circular area having an aspherical lens for correction of near and intermediate vision, surrounded by an annular area having a single focus spherical lens for correction of distance vision, said aspherical lens in the center having a diameter of appr~x~ately 2 rnm - 4 mm and said surrounding spherical lens having a diameter of a~p,oxi~ately 6.0 mm - 13.5 mm.
The above aspherical lens is a single focus or a multifocal lens.
Also, the contact lens of the present invention is produced using the mold casting method.
213522g The present invention is also useful for correcting presbyopia that is additionally burdened with astigm~ticm Existing lenses for correction of astigm~ti~m achieve a correction rate of only about 50% due to the unstable astigmatic axis, and require an addition to the lens, a prism, that does not provide comfortable fitting to the wearer.
The present invention does away with such prism and therefore does not sacrificecomfort for the wearer.
BRIEF DESCRIPTION OF DRAVVINGS
Fig. 1 is an enlarged schematic view of the contact lens embodying the present invention.
Fig. 2 is an enlarged sch~m~tic view of an eye fitted with the contact lens embodying the present invention.
Fig. 3 is a schematic view of the tracing of light rays through the contact lensembodying the present invention as fitted to a wearer.
DESCRIPTION OF PREFERRED EMBODIMENTS
Reference will be made to FIGS. 1 to 3 in the detailed description of the present invention.
FIG. 1 is a diagrammatic representation of the front view showing the front face of the contact lens embodying the present invention.
In actuality, the dividing lines between the aspherical and spherical areas represented by concentric circles are not physically visible.
Here, the circle (1) rep~ese,ll~ Center Aspheric Near Power (hereinafter referred ~o as "CANP"), a central circular area having an aspherical surface with diarneter of proximately 2.0 mm - 4.0 mm. The circle (2) surrounding said CANP relpresents Peripheral Spherical Distance Power (hereinafter referred to as "PSDP"), having a spherical surface with a diameter of approximately 6.0 mm - 13.5 mm.
The above described lens is a hydrophilic soft lens (L), made with such soft materials as hydroxiethyl metacrylate, acrylmonomer, vinylpyrrolidone (N-vinyl 2-pyrrolidone), and epoxy.
On the front face of the lens, the central aspherical surface has a diameter of approximately 2.0 mm - 4.0 mm, surrounded by an annular spherical area having a diameter of approximately 6.0 mm - 13.5 mm. The rear face forms a spherical surface conforming to the corneal surface of the .wearer's eye. The spherical and aspherical surfaces are smoothly contiguous so as not to show a distinctive boundary area or line.
FIG. 2 is a side view illustrating the contact lens of the present invention as fitted to an eye.
FIG. 3 is a schematic view of the tracing of light rays through the contact lensembodying the present invention and fitted to a wearer. Here, the light ray from a far distance (DP) passes through the spherical surface (2), and the light ray from a near distance (NP), through the aspherical surface (1), and form an exact image on the retina, thereby completely eradicating the blur circle that conventional contact lenses have been known to cause.
In a dark place where the pupil dilates and reading becomes difficult, the present invention employs a circular single focus lens to provide distance vision, whereas in a well lit place where the pupil contracts, the present invention commits an aspherical lens to provide not only distance vision but also near and intermediate vision.
213522g Contact lenses have been produced with hard lens materials for the last 25 years, but for the past lO to 15 years, soft lens materials have also been used.
Although the contact lens embodying the present invention may be manufactured using either hard lens or soft lens materials, the existing hard lens renders the correction of vision difficult, because as the lens moves around in the eye, the near vision area does not align to the center of the eyeball.
Also, after fitting to a wearer, a soft lens is far superior as compared with a hard lens in its ability to realign itself to the center of the eyeball after blinking.
The following are examples of using the present invention:
Patient A, age 59, fitted with the presbyopia col,cclillg contact lenses according to the present invention, achieved the following results. This patient does not require any correction on either of the eyes for distance vision, but requires corrective diopter of +0.50D on both eyes for activities requiring near vision, including reading. K
readings on this patient, measured by the Keratometer, are 7.85 mrn X 180/7.72 mm X 90 on both eyes. The lenses, made mainly of 2 HEMA material, have a hydration rate of 38%, line expansion rate of 1.18 and an index of refraction of 1.44.
The center thickness of the lens material is 0.06 mm, the curve radius, 8.4 mm, and the diameter of the lens, 14.0rnm.
Lens powers of the contact lenses fitted to the above patient are as follows.
CANP: + 0.50D
PSDP: Plano (No lens power) W~en fitted with the contact lenses according to the above lens powers, the patient achieved 1.2 visual acuity (Equivalent to 24/20 in the U.S. standard) both for .?.
213~229 near and distance vision. Therefore, this proved that the contact lens embodying the present invention is capable of correcting the vision that requires plano power for distance vision and some lens power for near vision, which was not possible through conventional bifocal contact lenses.
Patient B, age 50, fitted with the presbyopia correcting contact lenses according to the present invention, achieved the following results.
This patient's vision is encumbered by ~ctigm~ticm and myopia, having myopia diopter of -5.00 D on both eyes and astigm~ticm diopter of -l.OOD (astigm~ticm axis of 180) on the left eye. When reading, this patient requires corrective diopter of +1.00 D on both eyes. K re~lingc, measured by the Keratometer, are 7.80 mm X
180/7.59 mm X 90 on the left eye and 7.80 mm X 180/7.67 mm X 90 on the right eye. Contact lenses of the same material as specified in Example 1 were made for patient B.
Lens powers of the contact lenses fitted to the above patient are as follows.
CANP: -4.00D
PSDP: -5.00D
When fitted with the contact lenses according to the above lens powers, the patient achieved 1.2 visual acuity (Equivalent to 24/20 in the U.S. Standard) on both eyes.
The right eye of the above presbyopia patient indicated myopia and resbyopia, and the left eye indicated myopia and ~cti m~ticm as well as presbyopia.
Generally in cases of ~ctigm~ticm coming from an inclined axis or inverted ~cti~m~tic eyes, the use of ~tigm~ti~m lenses has achieved a correction rate of only about 50% due to the unstable actigm~tic axis. In order to solve the problem; of the unstable astigmatic axis, a prism has been added to the contact lens, which increased the thickness of the lens and made the experience of wearing the contact lens anuncomfortable affair. I
Since the contact lens embodying the present invention achieves the correction effects without adding a prism to the lens, it provides a comfortable fitting along with perfect correction for vision.
Even with the present invention, astigm~ti.cm over l.OOD is difficult to correct, whereas astigm~ti~m below l.OOD can be corrected perfectly. Considering, however, that approximately 50% of astigm~ti~m patients have an actigm~tic diopter of l.OOD
or less, the usefulness of the present invention is substantial.
Patient C, age 65, fitted with the presbyopia correcting contact lenses according to the present invention, achieved the following results.
This patient requires the corrective diopter of +O.SOD generally and, for reading and other near vision oriented tasks, of +2.00D for both eyes.
K re~-ling~, measured by the Keratometer, are 7.50 mm X 180/7.38 mrn X 90 on both eyes. Contact lenses of the same material as specified in Example 1 weremade for Patient C.
Lens powers of the contact lenses fitted to the above patient are as follows.
CANP: +2.50D
PSDP: +0.50D
When fitted with the contact lenses according to the above lens powers, the patient achieved 1.2 visual acuity (Equivalent to 24/20 in the U.S. Standard) on both eyes.
As seen from the above exarnples, the contact lens according to the present invention exhibits superior results in correcting cases of not only presbyopia but also myopia and astigm~ti~m added onto presbyopia.
The present invention provides correction for near and distance vision regardless of the size of the pupil area which varies according to the degree of lumination.
Optical areas on the lens ~e~ponsible for near vision and distance vision are smoothly contiguous so as not to indicate any visible dividing line. Further, the aspherical surface in the center of the lens functions as a multifocal lens that provides a clearly focused image on the retina of objects at a near distance. Therefore, the present invention has an effect of correcting both near and distance vision, not a selective correction often seen in the conventional lenses.
In addition, since the plesb~op;a co,~e~;ling contact lens according to the present invention is produced through a mold casting method, it is possible to produce arninute spherical surface with a high degree of ac~iula~;~, which has not been possible with the existing lathe-cutting m.oth-)-i thereby paving the way for mass production of the products with reduced costs and processes.
TITLE OF THE INVENTION
CONTACT LENS FOR CORRECTION OF PRESBYOPIA
BACKGROUND OF THE INVENTION
(a) Field of the Invention The present invention relates generally to a contact lens, and more specificallyto a hydrophilic, soft contact lens for correction of presbyopia, comprising in the circular center an aspherical lens area for near to intermediate vision, and, on its periphery, a spherical lens area for distance vision.
A person suffering from presbyopia is one whose ciliary body in the eye does not function at 100% level as age advances, in that the ciliary body does not adequately pull the lens of the eye to form a convex lens, resulting in blurred vision for objects at a near distance. Thelefore, a presbyopia patient needs corrective lenses that can provide normal vision for viewing distances of approximately 30 - 40 cm (13 - 16 inches).
Also, as a growing number of elderly people drive, they need adequate night vision for driving in the dark, as well as near distance vision for reading, regardless of the level the lumination. For this purpose, multifocal lenses have been developed, but they, or any other lenses for that matter, fall short of complete satisfaction.
If such multifocal lenses can provide correction for strabismus, ametropia or other astigm~ticm~, they will be much more useful.
- As used in the present specification and claims, the term, "multifocal lens", is defined as a lens having more than one focus depending on the position on the surface of the lens (usually a bifocal lens) which provides correction for far distance 213522~
or for reading, and capable of correcting the condition of presbyopia or plepre~byopic ametropia.
(b) Description of Prior Art Previously, bifocal contact lenses have been disclosed in, among others, the U.S.
patent Nos. 4199231 and 5125729.
The U.S. Patent No. 4199231 relates to a contact lens used for correction of presbyopia comprising on its rear face a spherical surface and on its front face an aspherical surface. Said invention pUI~ol ls to correct both near and distance visions, but has a drawback that the corrected vision, both for near and distance, is not clear.
Said invention also purports to minimi7e the blur circle, (a distorted image of near and distant objects formed on the retina when using a spherical lens), through using an aspherical lens, but the actual success rate is only about 50%, and diz7iness is frequently caused.
The U.S. Patent No. 5125729 relates to a multifocal lens comprising on its front face a central circular area having a spherical surface for distance vision, on its periphery, a surrounding annular area having an aspherical surface for near vision, and on yet a further outer periphery thereof, another surrounding annular area having a spherical lens for distance vision. Said invention has a drawback in that proper focus can be achieved only through adjusting the degree of lumination, since the correction area for distance vision is positioned in the central portion of the lens. To illustrate, the pupil of the eye dilates at night to cover much of the near vision area of the lens, thereby disturbing distance vision. Therefore, a potentially h~7~rdous situation may occur when driving or doing other activities at night that require distance vision.
Conversely, in a well lit area, the pupil contracts to cover only the distance vision area, thereby causing blurred vision for reading or other activities that require near vision.
213522g In addition, conventional bifocal lenses have been practically useless in cases where lens power is required for the near vision range, but not for the distance vision range (plano power).
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a contact lens for correction of presbyopia, without the existing drawbacks described above, that can provide near, intermediate and ~ nce vision regardless of whether in dark or well lit places. A
contact lens according to the present invention comprises a central circular area having an aspherical surface surrounded by an annular area having a spherical surface, and is capable of providing correction for near and intermediate vision as well as distance vlslon.
It is another purpose of the present invention to provide a mold casting method of producing the contact lens embodying the present invention that can produce aminute spherical surface with a high degree of accuracy, which has not beei~ possible with the conventional lathe-cutting method.
To achieve the above purposes, the contact lens of the present invention comprises a central circular area having an aspherical lens for correction of near and intermediate vision, surrounded by an annular area having a single focus spherical lens for correction of distance vision, said aspherical lens in the center having a diameter of appr~x~ately 2 rnm - 4 mm and said surrounding spherical lens having a diameter of a~p,oxi~ately 6.0 mm - 13.5 mm.
The above aspherical lens is a single focus or a multifocal lens.
Also, the contact lens of the present invention is produced using the mold casting method.
213522g The present invention is also useful for correcting presbyopia that is additionally burdened with astigm~ticm Existing lenses for correction of astigm~ti~m achieve a correction rate of only about 50% due to the unstable astigmatic axis, and require an addition to the lens, a prism, that does not provide comfortable fitting to the wearer.
The present invention does away with such prism and therefore does not sacrificecomfort for the wearer.
BRIEF DESCRIPTION OF DRAVVINGS
Fig. 1 is an enlarged schematic view of the contact lens embodying the present invention.
Fig. 2 is an enlarged sch~m~tic view of an eye fitted with the contact lens embodying the present invention.
Fig. 3 is a schematic view of the tracing of light rays through the contact lensembodying the present invention as fitted to a wearer.
DESCRIPTION OF PREFERRED EMBODIMENTS
Reference will be made to FIGS. 1 to 3 in the detailed description of the present invention.
FIG. 1 is a diagrammatic representation of the front view showing the front face of the contact lens embodying the present invention.
In actuality, the dividing lines between the aspherical and spherical areas represented by concentric circles are not physically visible.
Here, the circle (1) rep~ese,ll~ Center Aspheric Near Power (hereinafter referred ~o as "CANP"), a central circular area having an aspherical surface with diarneter of proximately 2.0 mm - 4.0 mm. The circle (2) surrounding said CANP relpresents Peripheral Spherical Distance Power (hereinafter referred to as "PSDP"), having a spherical surface with a diameter of approximately 6.0 mm - 13.5 mm.
The above described lens is a hydrophilic soft lens (L), made with such soft materials as hydroxiethyl metacrylate, acrylmonomer, vinylpyrrolidone (N-vinyl 2-pyrrolidone), and epoxy.
On the front face of the lens, the central aspherical surface has a diameter of approximately 2.0 mm - 4.0 mm, surrounded by an annular spherical area having a diameter of approximately 6.0 mm - 13.5 mm. The rear face forms a spherical surface conforming to the corneal surface of the .wearer's eye. The spherical and aspherical surfaces are smoothly contiguous so as not to show a distinctive boundary area or line.
FIG. 2 is a side view illustrating the contact lens of the present invention as fitted to an eye.
FIG. 3 is a schematic view of the tracing of light rays through the contact lensembodying the present invention and fitted to a wearer. Here, the light ray from a far distance (DP) passes through the spherical surface (2), and the light ray from a near distance (NP), through the aspherical surface (1), and form an exact image on the retina, thereby completely eradicating the blur circle that conventional contact lenses have been known to cause.
In a dark place where the pupil dilates and reading becomes difficult, the present invention employs a circular single focus lens to provide distance vision, whereas in a well lit place where the pupil contracts, the present invention commits an aspherical lens to provide not only distance vision but also near and intermediate vision.
213522g Contact lenses have been produced with hard lens materials for the last 25 years, but for the past lO to 15 years, soft lens materials have also been used.
Although the contact lens embodying the present invention may be manufactured using either hard lens or soft lens materials, the existing hard lens renders the correction of vision difficult, because as the lens moves around in the eye, the near vision area does not align to the center of the eyeball.
Also, after fitting to a wearer, a soft lens is far superior as compared with a hard lens in its ability to realign itself to the center of the eyeball after blinking.
The following are examples of using the present invention:
Patient A, age 59, fitted with the presbyopia col,cclillg contact lenses according to the present invention, achieved the following results. This patient does not require any correction on either of the eyes for distance vision, but requires corrective diopter of +0.50D on both eyes for activities requiring near vision, including reading. K
readings on this patient, measured by the Keratometer, are 7.85 mrn X 180/7.72 mm X 90 on both eyes. The lenses, made mainly of 2 HEMA material, have a hydration rate of 38%, line expansion rate of 1.18 and an index of refraction of 1.44.
The center thickness of the lens material is 0.06 mm, the curve radius, 8.4 mm, and the diameter of the lens, 14.0rnm.
Lens powers of the contact lenses fitted to the above patient are as follows.
CANP: + 0.50D
PSDP: Plano (No lens power) W~en fitted with the contact lenses according to the above lens powers, the patient achieved 1.2 visual acuity (Equivalent to 24/20 in the U.S. standard) both for .?.
213~229 near and distance vision. Therefore, this proved that the contact lens embodying the present invention is capable of correcting the vision that requires plano power for distance vision and some lens power for near vision, which was not possible through conventional bifocal contact lenses.
Patient B, age 50, fitted with the presbyopia correcting contact lenses according to the present invention, achieved the following results.
This patient's vision is encumbered by ~ctigm~ticm and myopia, having myopia diopter of -5.00 D on both eyes and astigm~ticm diopter of -l.OOD (astigm~ticm axis of 180) on the left eye. When reading, this patient requires corrective diopter of +1.00 D on both eyes. K re~lingc, measured by the Keratometer, are 7.80 mm X
180/7.59 mm X 90 on the left eye and 7.80 mm X 180/7.67 mm X 90 on the right eye. Contact lenses of the same material as specified in Example 1 were made for patient B.
Lens powers of the contact lenses fitted to the above patient are as follows.
CANP: -4.00D
PSDP: -5.00D
When fitted with the contact lenses according to the above lens powers, the patient achieved 1.2 visual acuity (Equivalent to 24/20 in the U.S. Standard) on both eyes.
The right eye of the above presbyopia patient indicated myopia and resbyopia, and the left eye indicated myopia and ~cti m~ticm as well as presbyopia.
Generally in cases of ~ctigm~ticm coming from an inclined axis or inverted ~cti~m~tic eyes, the use of ~tigm~ti~m lenses has achieved a correction rate of only about 50% due to the unstable actigm~tic axis. In order to solve the problem; of the unstable astigmatic axis, a prism has been added to the contact lens, which increased the thickness of the lens and made the experience of wearing the contact lens anuncomfortable affair. I
Since the contact lens embodying the present invention achieves the correction effects without adding a prism to the lens, it provides a comfortable fitting along with perfect correction for vision.
Even with the present invention, astigm~ti.cm over l.OOD is difficult to correct, whereas astigm~ti~m below l.OOD can be corrected perfectly. Considering, however, that approximately 50% of astigm~ti~m patients have an actigm~tic diopter of l.OOD
or less, the usefulness of the present invention is substantial.
Patient C, age 65, fitted with the presbyopia correcting contact lenses according to the present invention, achieved the following results.
This patient requires the corrective diopter of +O.SOD generally and, for reading and other near vision oriented tasks, of +2.00D for both eyes.
K re~-ling~, measured by the Keratometer, are 7.50 mm X 180/7.38 mrn X 90 on both eyes. Contact lenses of the same material as specified in Example 1 weremade for Patient C.
Lens powers of the contact lenses fitted to the above patient are as follows.
CANP: +2.50D
PSDP: +0.50D
When fitted with the contact lenses according to the above lens powers, the patient achieved 1.2 visual acuity (Equivalent to 24/20 in the U.S. Standard) on both eyes.
As seen from the above exarnples, the contact lens according to the present invention exhibits superior results in correcting cases of not only presbyopia but also myopia and astigm~ti~m added onto presbyopia.
The present invention provides correction for near and distance vision regardless of the size of the pupil area which varies according to the degree of lumination.
Optical areas on the lens ~e~ponsible for near vision and distance vision are smoothly contiguous so as not to indicate any visible dividing line. Further, the aspherical surface in the center of the lens functions as a multifocal lens that provides a clearly focused image on the retina of objects at a near distance. Therefore, the present invention has an effect of correcting both near and distance vision, not a selective correction often seen in the conventional lenses.
In addition, since the plesb~op;a co,~e~;ling contact lens according to the present invention is produced through a mold casting method, it is possible to produce arninute spherical surface with a high degree of ac~iula~;~, which has not been possible with the existing lathe-cutting m.oth-)-i thereby paving the way for mass production of the products with reduced costs and processes.
Claims (4)
1. A contact lens for correcting presbyopia comprising a aspherical lens formed at a central part for correction of near vision and a single focus spherical lens formed at annular periphery of said aspherical lens for correction of distance vision.
2. A contact lens according to claim 1, wherein the aspherical lens is a single focus lens.
3. A contact lens according to claim 1, wherein the aspherical lens is a multifocal lens.
4. A contact lens according to claim 1, wherein the central aspherical lens is approximately 2 mm - 4 mm in diameter and the peripheral single focus lens is approximately 6.0 mm - 13.5 mm in diameter.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR6148/1994 | 1994-03-26 | ||
| KR19940006148 | 1994-03-26 | ||
| KR17328/1994 | 1994-07-18 | ||
| KR1019940017328A KR0129588B1 (en) | 1994-03-26 | 1994-07-18 | Contact lens |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2135229A1 true CA2135229A1 (en) | 1995-09-27 |
Family
ID=26630265
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2135229 Abandoned CA2135229A1 (en) | 1994-03-26 | 1994-11-07 | Contact lens for correction of presbyopia |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPH08152583A (en) |
| KR (1) | KR0129588B1 (en) |
| CA (1) | CA2135229A1 (en) |
| GB (1) | GB2288033A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW532488U (en) * | 1998-02-11 | 2003-05-11 | Euro Lens Technology S P A | A progressive multifocal contact lens suitable for compensating presbyopia |
| DE19933775A1 (en) * | 1999-07-19 | 2001-02-08 | Hecht Gmbh Kontaktlinsen | Contact lens or intraocular lens with long-range and near-effect zones |
| US6695449B2 (en) * | 2000-08-17 | 2004-02-24 | Novartis Ag | Lens design to enhance vision quality |
| KR101390215B1 (en) * | 2012-11-14 | 2014-04-30 | (주)고려아이텍 | Soft contact lens for presbyopia and method for thereof |
| KR101490778B1 (en) * | 2014-09-30 | 2015-02-06 | 김진태 | Calibration lens can be seen ultra short distance and device thereof |
| KR101578327B1 (en) | 2015-06-04 | 2015-12-16 | 구오섭 | Contact lens for presbyopia |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2592726A1 (en) * | 1986-01-08 | 1987-07-10 | Capez Pierre | MULTIFOCAL CONTACT LENS AND MANUFACTURING METHOD THEREOF |
| US5236452A (en) * | 1987-07-02 | 1993-08-17 | Nordan Lee T | Intraocular multifocal lens |
| JPH01144013A (en) * | 1987-12-01 | 1989-06-06 | Nippon Contact Lens:Kk | Contact lens and production thereof |
| FR2632079B1 (en) * | 1988-05-27 | 1990-09-28 | Capez Pierre | MULTIFOCAL CONTACT LENS |
| FR2642854B1 (en) * | 1989-02-03 | 1991-05-03 | Essilor Int | OPTICAL LENS WITH SIMULTANEOUS VISION FOR PRESBYTIA CORRECTION |
| DE4012478A1 (en) * | 1990-04-19 | 1991-10-24 | Heinrich Woehlk Inst Fuer Cont | CONTACT LENS WITH STABILIZATION |
-
1994
- 1994-07-18 KR KR1019940017328A patent/KR0129588B1/en not_active Expired - Fee Related
- 1994-10-31 GB GB9421896A patent/GB2288033A/en not_active Withdrawn
- 1994-11-07 CA CA 2135229 patent/CA2135229A1/en not_active Abandoned
- 1994-12-14 JP JP31042894A patent/JPH08152583A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2288033A (en) | 1995-10-04 |
| KR950026488A (en) | 1995-10-16 |
| GB9421896D0 (en) | 1994-12-14 |
| JPH08152583A (en) | 1996-06-11 |
| KR0129588B1 (en) | 1998-04-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |