US4194815A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semi-scleral contact lens
Assignee: Dow Silicones Corp
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Filing: 1978-06-28
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Granted: 1980-03-25
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Expires: 1998-06-28
Abstract
Abstract The inner surface of a semi-scleral contact lens is shaped relative to the topography of an individual eyeball to achieve central contact and edge contact with tearfilm clearance therebetween. The lens has improved centering properties. The lens includes an optical zone which is the spherical equivalent of the radius of curvature of the cornea at its optical centerline and the corneal dimensional diameter. The optical zone has a sagittal depth which is dependent on the topography of the cornea. The lens also includes a conoid section which is tangent to the edge of the optical zone and which extends from the edge of the optical zone to a selected point over the limbus. A peripheral curve having an individual radius of curvature extends from the selected point to the edge of the lens.
Inventors
- 👤 Wayne E. Trombley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 08:04
CPC Classifications
G; G02; G02C; G02C7/00; G02C7/02; G02C7/04
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
194 words
A semi-scleral contact lens having an interior surface shaped relative to the topography of an individual eyeball so that the lens exhibits central contact and edge contact with tearfilm clearance therebetween and tear exchange with blinking, the lens comprising: (a) an optical zone which is the spherical equivalent of the radius of curvature (k) of the cornea at its optical centerline and the corneal dimensional diameter (y), the optical zone having a sagittal depth described by the formula ##EQU6## where a is k/Sf, Sf is 1-E 2 , and E is the degree of eccentricity of the ellipse described by the cornea, and the optical zone having a radius of curvature described by the formula ##EQU7## (b) a conic section between the circumference of the optical zone and a selected point over the limbus, the conoid being tangent to the optical zone at its circumference; and (c) a curved peripheral section between the selected point and the edge of the lens, the peripheral section having a radius of curvature which is perpendicular to the conoid section at the selected point and which extends from the selected point to the optical centerline of the cornea.
Claim 2
Dependent Claim
194 words
A semi-scleral contact lens having an interior surface shaped relative to the topography of an individual eyeball so that the lens exhibits central contact and edge contact with tearfilm clearance therebetween and tear exchange with blinking, the lens comprising: (a) an optical zone which is the spherical equivalent of the radius of curvature (k) of the cornea at its optical centerline and the corneal dimensional diameter (y), the optical zone having a sagittal depth described by the formula ##EQU6## where a is k/Sf, Sf is 1-E 2 , and E is the degree of eccentricity of the ellipse described by the cornea, and the optical zone having a radius of curvature described by the formula ##EQU7## (b) a conic section between the circumference of the optical zone and a selected point over the limbus, the conoid being tangent to the optical zone at its circumference; and (c) a curved peripheral section between the selected point and the edge of the lens, the peripheral section having a radius of curvature which is perpendicular to the conoid section at the selected point and which extends from the selected point to the optical centerline of the cornea.
Claim 3
Dependent Claim
11 words
The lens of claim 1 wherein the outer surface is lenticular.
Claim 4
Dependent Claim
14 words
The lens of claim 1 wherein the lens is formed from a resilient material.
Claim 5
Dependent Claim
13 words
The lens of claim 3 wherein the resilient material is a silicone rubber.
Claim 6
Dependent Claim
23 words
The lens of claim 1 wherein the radius of curvature of the cornea (k) is between about 7.4 mm and about 8.4 mm.
Claim 7
Dependent Claim
20 words
The lens of claim 1 wherein the corneal dimensional diameter (y) is from about 9 mm to about 11 mm.
Claim 8
Dependent Claim
19 words
The lens of claim 1 wherein the selected point defines a circle having a diameter of about 11.65 mm.
Claim 9
Dependent Claim
17 words
The lens of claim 1 wherein the lens diameter is from about 13 to about 17 mm.
Claim 10
Dependent Claim
18 words
The lens of claim 1 wherein the eccentricity of the eye is from about 0.2 to about 0.7.
Claim 11
Independent Claim
198 words
A method for shaping the interior surface of a semi-scleral contact lens relative to the topography of an individual eyeball so that the lens exhibits central contact and edge contact with tearfilm clearance therebetween and tearfilm exchange with blinking, the method comprising: (a) forming an optical zone which is the spherical equivalent of the radius of curvature (k) of the cornea at its optical centerline and the corneal diameter (y), the optical zone having a sagittal depth described by the formula ##EQU8## where a is k/Sf, Sf is 1-E 2 , and E is the degree of eccentricity of the ellipse described by the cornea, and the optical zone having a radius of curvature described by the formula ##EQU9## (b) forming a conic section between the circumference of the optical zone and a selected point over the limbus, the conoid being tangent to the optical zone at its circumference; and (c) forming a peripheral curve between the selected point and the edge of the lens, the peripheral curve having a radius of curvature which is perpendicular to the conoid section at the selected point, and which extends from the selected point to the optical centerline of the cornea.
Claim 12
Independent Claim
198 words
A method for shaping the interior surface of a semi-scleral contact lens relative to the topography of an individual eyeball so that the lens exhibits central contact and edge contact with tearfilm clearance therebetween and tearfilm exchange with blinking, the method comprising: (a) forming an optical zone which is the spherical equivalent of the radius of curvature (k) of the cornea at its optical centerline and the corneal diameter (y), the optical zone having a sagittal depth described by the formula ##EQU8## where a is k/Sf, Sf is 1-E 2 , and E is the degree of eccentricity of the ellipse described by the cornea, and the optical zone having a radius of curvature described by the formula ##EQU9## (b) forming a conic section between the circumference of the optical zone and a selected point over the limbus, the conoid being tangent to the optical zone at its circumference; and (c) forming a peripheral curve between the selected point and the edge of the lens, the peripheral curve having a radius of curvature which is perpendicular to the conoid section at the selected point, and which extends from the selected point to the optical centerline of the cornea.
Claim 13
Dependent Claim
29 words
The method of claim 10 wherein the shape of the interior surface of the lens is incorporated into a mold and wherein the lens is formed using the mold.
Claim 14
Dependent Claim
16 words
The method of claim 10 wherein the interior surface of the lens is formed by machining.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-03-25 | 1983-09-24 | 1984-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-03-25 | 1987-09-24 | 1988-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-03-25 | 1991-09-24 | 1992-03-25 | $7700.00 | Window Closed / Lapsed |