Oxygen permeable bifocal contact lenses and their manufacture
US5170192A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 29, 1990 |
| Grant date | Dec 8, 1992 |
| Priority date | — |
| Expiry date | Nov 29, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C2202/16
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
An oxygen permeable bifocal contact lens with a Dk of at least 10.times.10.sup.-11 in which a distance vision portion having a refractive index of not more than 1.49 is formed as a preform in which there is provided a recess, and a near distance vision portion having a refractive index of at least 1.540 is formed by filling the recess with a monomer mixture and polymerizing. It is preferred that the distance vision portion be formed as an interpenetrating network copolymer by partially polymerizing one monomer mixture to a predetermined relative viscosity and then adding a second monomer mixture and copolymerizing the resulting mixture. The near distance vision portion may also be formed as an interpenetrating network in the same manner.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.