Soft contact lens with a back surface whose central and intermediate portions are formed by different ellipsoidal surfaces continuously contiguous to each other
US5502517A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 26, 1994 |
| Grant date | Mar 26, 1996 |
| Priority date | — |
| Expiry date | Apr 26, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C7/04
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The present invention was developed to improve wearing conditions of a soft contact lens while improving production efficiency of the soft contact lens and assuring an enhanced optical effect offered by the lens. The present soft contact lens has a back surface, a front surface and a connecting surface. The back surface of the lens is constituted by: a central portion formed by an ellipsoidal surface with an eccentricity in the range of 0.2-0.7 and a vertex radius of curvature in the range of 5.00-10.00 mm; an intermediate portion which is located at the periphery of the central portion so as to surround the central portion and is formed by another ellipsoidal surface with an eccentricity in the range of 0.2-0.7, at least one of the eccentricity and a vertex radius of curvature of the ellipsoidal surface of the intermediate portion being different from that of the ellipsoidal surface of the central portion; and a marginal portion which is located around the periphery of the intermediate portion and formed so that the marginal portion is spaced away from the cornea such that an axial clearance between the cornea and the back surface of the contact lens increases with an increase in …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.