Patent ID: 6685315
Filing Date: 2004-02-03
Classification: A61F,G02B,G02C

Abstract:
A bifocal contact lens having a viewing area generally corresponding to the maximum pupil area of the wearer, said viewing area having a central circular refractive zone having a first focal length corresponding to distance vision or reading vision and a plurality of annular refractive zones which alternate between a second focal length and said first focal length corresponding to the other of reading and distance vision as they extend outwardly from said central zone, wherein at each pupil size between a minimum and a maximum the relative areas of the distance and reading zones are between 40:60 and 60:40, the total number of zones comprises at least 30, the zones are alternately flatter or steeper than the cornea and there is a progressive increase in negative power in at least some of the zones of the same character towards the periphery of the viewing area.