Contact lens with transition
US6871953B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 29, 2003 |
| Grant date | Mar 29, 2005 |
| Priority date | — |
| Expiry date | Oct 20, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C7/045
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A monocentric bifocal contact lens with upper and lower optical power zones is connected by a transition comprising a family of sigmoidal curves. The sigmoidal curve begins with a common tangent at the boundary of the near zone and, with a reversal of sign from the near zone curve, climbs with increasing positive slope to an inflection point, whereupon it continues to climb with decreasing positive slope until reaching the distance zone curve, with which it has a common tangent. There is no discontinuity in the first derivative of the curve throughout its length. A sigmoidal curve can be constructed from numerous mathematical functions, examples of which include polynomial, conic, transendental, or cumulative distribution curves.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.