Patent ID: 6871953
Filing Date: 2005-03-29
Classification: G02C

Abstract:
1. A bifocal contact lens formed of at least one optical material and comprising, a back surface of generally concave shape, and a front surface of generally convex shape, said front surface joining said back surface at an edge perimeter, at least one of said surfaces comprising an upper zone of optical power and a lower zone of different optical power, said upper and lower zones connected by a transition, a region between said bifocal area and said edge perimeter comprising a peripheral zone, said upper zone and said lower zone together with said transition comprising a bifocal area that is monocentric, said transition comprising a family of curves with an upper and a lower boundary and having a plurality of sigmoidal shapes, whereby said lens provides a wearer with vision that is free of image jump and allows minimal resistance to lid movement across said lens.