Progressive multifocal ophthalmic lens
US5708493A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 19, 1995 |
| Grant date | Jan 13, 1998 |
| Priority date | — |
| Expiry date | Oct 19, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C7/066
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A progressive multifocal ophthalmic lens is provided having an aspherical surface with a mean sphere and a cylinder at every point. The aspherical surface has a distance vision portion, with a control point for distance vision, a near vision portion with a control point for near vision, and an intermediate vision portion between the near vision portion and the distance vision portion. A power addition value A is defined as a variation in mean sphere between the control point for distance vision and the control point for near vision portion. A base B is defined as a value of mean sphere at the control point for distance vision. A width of the near vision portion varies not only as a function of the power addition value A, but also as a function of the value B of the base. The invention thereby ensures the presence of a substantially constant object field for all values of the power addition and of the base.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.