Large diameter positive power ophthalmic lens
US4978211A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 10, 1989 |
| Grant date | Dec 18, 1990 |
| Priority date | — |
| Expiry date | Oct 10, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C7/02
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A positive power ophthalmic lens has a central optically active area the diameter of which is at most equal to the diameter of its geometrical contour. It has an optional peripheral merging area around the central optically active area, between the latter and the geometrical contour. The diameter D.sub.1 in millimeters of the central optically active area is related to the power P of the lens in diopters by a general equation of the type: EQU D.sub.1 =a-b.p where a is a numerical parameter taking a value between 84 and 89 and b is a numerical parameter taking a value between 4 and 4.9. This equation makes it possible to obtain well corrected positive power ophthalmic lenses with a large diameter that are relatively light in weight.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.