US4593981A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bifocal contact lens
Assignee: Master Contact Lens Labs Inc
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Filing: 1983-05-06
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Granted: 1986-06-10
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Expires: 2003-05-06
Abstract
Abstract A bifocal contact lens having a curved anterior (outside) surface and a curved posterior (inside) surface is formed from a lens blank. The lens corrects for near vision, for example, of a presbyope, by a full-hemisphere spherical depression (seg) in the center of the posterior surface which becomes filled with tear liquid. The ring-like peripheral area, beyond the depression, at the posterior surface, has a curvature which matches the cornea of the wearer and permits a gap for tear liquid flow, the curvature of the peripheral area having a larger radius than the radius of the depression. The ring-like zone formed by the junction of the depression and the peripheral area is smoothed by a velveteen cloth polishing operation to form a transparent curved zone which permits near, far and intermediate distance viewing by the wearer through the center of the lens and without movement of the lens on the cornea.
Inventors
- 👤 Joseph F. Scilipoti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:51
CPC Classifications
G; G02; G02C; G02C7/00; G02C7/02; G02C7/04; G02C7/041; G02C7/044; G02C7/042
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
202 words
A bifocal contact lens made of a transparent contact-lens material and having an anterior surface of a selected curvature and a posterior concave surface having a peripheral portion for near viewing and having a spherical curvature and with a radius of curvature designed to fit the surface of a wearer's cornea with a parallel fit, and not a tight fit, so that a layer of tear liquid is maintained in a gap between said posterior surface and said cornea, and a central portion for distant viewing in the form of a depression in said posterior surface for holding tear liquid, the diameter of said central portion being at least 3.5 mm and its curvature being a spherical curve, which tear liquid in the depression acts as part of the lens system, the surface of said depression having a radius of curvature shorter than that of said peripheral portion; and a transparent zone of said posterior surface at the junction of said peripheral and central poritons, which zone is of rounded and smooth shape and from 0.1 mm to 0.4 mm in which so as to provide a gradual transition from the curvature of said peripheral portion to the curvature of said depression.
Claim 2
Dependent Claim
202 words
A bifocal contact lens made of a transparent contact-lens material and having an anterior surface of a selected curvature and a posterior concave surface having a peripheral portion for near viewing and having a spherical curvature and with a radius of curvature designed to fit the surface of a wearer's cornea with a parallel fit, and not a tight fit, so that a layer of tear liquid is maintained in a gap between said posterior surface and said cornea, and a central portion for distant viewing in the form of a depression in said posterior surface for holding tear liquid, the diameter of said central portion being at least 3.5 mm and its curvature being a spherical curve, which tear liquid in the depression acts as part of the lens system, the surface of said depression having a radius of curvature shorter than that of said peripheral portion; and a transparent zone of said posterior surface at the junction of said peripheral and central poritons, which zone is of rounded and smooth shape and from 0.1 mm to 0.4 mm in which so as to provide a gradual transition from the curvature of said peripheral portion to the curvature of said depression.
Claim 3
Dependent Claim
16 words
A contact lens as in claim 1 wherein said anterior surface has a uniform spherical curvature.
Claim 4
Dependent Claim
28 words
A contact lens as in claim 1 wherein said depression is a full hemisphere whose radius is smaller than the radius of the curvature of said peripheral portion.
Claim 5
Independent Claim
212 words
A method of making a bifocal contact lens having anterior and posterior surfaces which consists of providing an anterior surface of selected curvature on one side of a lens blank of transparent contact lens material; providing a central depression for distant viewing on the posterior surface having a diameter of at least 3.5 mm, a spherical curvature, and a radius of curvature less than that of the curvature of the cornea of the wearer of the lens and also a peripheral portion for near viewing with a spherical curvature on the posterior surface beyond said depression and having a radius of curvature substantially the same as that of the cornea of the wearer of the lens, to form the lens with a parallel fit, and not a tight fit, and with a gap filled with tear fluid between said posterior surface and said cornea; and then blending the transition zone between the peripheral and central portions of said posterior surface to form an annular zone of 0.1 mm to 0.4 mm in width by polishing with a tool having a radius intermediate the radii of said central depression and said peripheral portion, so as to provide a gradual and smooth and transparent transition zone from the peripheral portion to the said depression.
Claim 6
Independent Claim
212 words
A method of making a bifocal contact lens having anterior and posterior surfaces which consists of providing an anterior surface of selected curvature on one side of a lens blank of transparent contact lens material; providing a central depression for distant viewing on the posterior surface having a diameter of at least 3.5 mm, a spherical curvature, and a radius of curvature less than that of the curvature of the cornea of the wearer of the lens and also a peripheral portion for near viewing with a spherical curvature on the posterior surface beyond said depression and having a radius of curvature substantially the same as that of the cornea of the wearer of the lens, to form the lens with a parallel fit, and not a tight fit, and with a gap filled with tear fluid between said posterior surface and said cornea; and then blending the transition zone between the peripheral and central portions of said posterior surface to form an annular zone of 0.1 mm to 0.4 mm in width by polishing with a tool having a radius intermediate the radii of said central depression and said peripheral portion, so as to provide a gradual and smooth and transparent transition zone from the peripheral portion to the said depression.
Claim 7
Dependent Claim
26 words
A method as defined in claim 4 in which the step of blending is performed by polishing with a tool whose surface consists of velveteen cloth.
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) | 1989-06-09 | 1989-12-09 | 1990-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-09 | 1993-12-09 | 1994-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-09 | 1997-12-09 | 1998-06-10 | $7700.00 | Window Closed / Lapsed |