Method of making hydrogel contact lenses having aspheric front surfaces

• US 4,909,621 A
• Filed: 08/17/1987
• Issued: 03/20/1990
• Est. Priority Date: 08/17/1987
• Status: Expired due to Term

• Current Assignee: Aspheric Lens Company
• Original Assignee: Cyril C.H. Evans
• Inventors: Evans, Cyril C. H.
• Primary Examiner(s): Arnold, Bruce Y.
• Assistant Examiner(s): Callaghan, Terry S.
• Application Number:
  US07/085,755
• Time in Patent Office: 946 Days
• Field of Search: 351/177, 351/161, 351/160 H
• US Class Current: 351/161
• CPC Class Codes: B23Q 35/102 of one line
• CPC Class Codes: B24B 13/046 using a pointed tool or scraper-like tool B24B13/015 and B24B13/065 take precedence
• CPC Class Codes: B24B 17/025 for grinding rotating workpieces (three dimensional)
• CPC Class Codes: B29D 11/00932 Combined cutting and grinding thereof
• CPC Class Codes: G02C 7/04 Contact lenses for the eyes disinfection or sterilisation of contact lenses A61L12/00

Abstract

A contact lens of soft, pliable opthalmic plastic material, said lens when in its dehydrated state having a spherical back surface which in its hydrated state conforms to the corneal curvature of the wearer'"'"'s eye and, when in its dehydrated state, having an aspheric front surface which is a surface of revolution of polar coordinate form, having an asphericity which is a function of (n)[f]<sin(a)> where (a) is the polar angle, and (n) is a radial offset of a tool-controlling circular surface.

Claims

1. A contact lens of soft, pliable opthalmic plastic material, said lens when in its dehydrated state having a spherical back surface which in its hydrated state conforms to the corneal curvature of the wearer'"'"'s eye and, when in its dehydrated state, having an aspheric front surface which is a surface of revolution of polar coordinate form, having an asphericity which is a function of (n) {sin(a)} where (a) is the polar angle, and (n) is a radial offset of a tool-controlling circular surface and is equal to at least about 0.013 mm.

2. A contact lens as defined in claim 1 wherein the equation of the aspheric front surface, in polar form, is p=r+(n) {sin (m)-sin (m-a)}, where (m) is a rotational angle of the radial offset (n) and is equal to at least about 40°

.

3. A contact lens of soft pliable opthalmic plastic material, said lens when in its dehydrated state having a spherical back surface which in its hydrated state conforms to the corneal curvature of the wearer'"'"'s eye and, when in its dehydrated state having an aspheric front surface which is a surface of revolution whose asphericity, in polar form and having a polar angle, is a function of {sin (m)-sin (ma-a)} where (a) is the polar angle and (m) is a fixed angle.