Concentric annular ring lens designs for astigmatic presbyopes
US5847802A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 14, 1997 |
| Grant date | Dec 8, 1998 |
| Priority date | — |
| Expiry date | Jul 14, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C7/06
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Concentric lens designs are disclosed for astigmatic presbyopes which comprise at least one surface which has a circular central portion and a plurality of concentric annular rings with at least three separate optical powers corresponding to a prescription for a patient and corresponding to 1) a basic distance spherical prescription Rx, 2) a near add spherical prescription Rx, and 3) a spherical prescription corresponding to the full, or preferably a fraction of the, cylindrical prescription Rx. An astigmatic presbyopic prescription contains an astigmatic correction, normally in the nature of a cylindrical prescription which specifies both the cylindrical optical power and the orientation of the cylindrical axis. The cylindrical prescription is taken into account in the design of the lens, but not with a cylindrical optical surface. Instead, the present invention recognizes that the brain can effectively discriminate between separate competing images by accepting an in-focus image and rejecting an out-of-focus image. Accordingly, a portion of the lens is provided with a spherical surface corresponding to the cylindrical prescription, or more preferably a fraction of the full cylind…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.