Oxygen permeable bifocal contact lenses and their manufacture
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United States of America Patent
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-
Dec 8, 1992
Grant Date -
N/A
app pub date -
Nov 29, 1990
filing date -
Nov 29, 1990
priority date (Note) -
Expired
status (Latency Note)
Importance
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.
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Cited Art Landscape
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