Progressive multifocal ophthalmic lens
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United States of America Patent
Stats
-
Dec 14, 1993
Grant Date -
N/A
app pub date -
Oct 28, 1992
filing date -
Nov 12, 1991
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
The lens has an aspherical surface having a zone for far vision, a zone for near vision, and between these two zones, a zone for intermediate vision, with a meridian curve along which the curvature of the surface varies progressively and which is inclined from top to bottom towards the nose side of the lens, at least in the intermediate zone. A portion of the meridian curve situated in the intermediate and near zones is divided into a first segment at an angle .alpha. to the vertical where the value of .alpha. is an increasing function of the power addition A of the lens, and a second segment at an angle .omega. to the vertical where .omega. is smaller than .alpha.. At the point where the two segments meet, the mean sphere value of the surface corresponds to a power addition lying in the range 0.8 to 0.92 times the nominal power addition of the lens.
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Cited Art Landscape
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