Simultaneous vision optical lens for correcting presbyopia
US4976534A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 22, 1990 |
| Grant date | Dec 11, 1990 |
| Priority date | — |
| Expiry date | Jan 22, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C7/06
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The proximity P of a simultaneous vision optical lens for correcting presbyopia is defined as the reciprocal of the distance D at which a light ray parallel to and at a distance h from its axis crosses the axis after passing through the lens. The curve representing the proximity P of the lens lies between a lower envelope curve P.sub.inf and an upper envelope curve P.sub.sup satisfying the following equations: EQU P.sub.inf =f(h)=(.SIGMA.A'.sub.i h.sup.i)+P.sub.VL EQU P.sub.sup =f(h)=(.SIGMA.A".sub.i h.sup.i)+P.sub.VL in which P.sub.VL is the proximity for distant vision and A'.sub.i, A".sub.i are numeric coefficients depending on the proximity addition added for near vision to the proximity for far vision. The lens may be implemented as a contact lens, an intra-ocular implant or an intra-corneal lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.