Patent ID: 6186627
Filing Date: 2001-02-13
Classification: G02C

Abstract:
A progressive power lens having a negative dioptric power for distance vision, wherein a progressive surface is formed on the back surface of said progressive power lens;wherein the value of a surface power Pf.sub.m of said progressive surface in the main meridional plane at a first point on the main meridian in a distance portion of said progressive power lens is less than the value of a surface power Pf.sub.s of said progressive surface in a plane perpendicular to said main meridional plane at said first point (Pf.sub.m <Pf.sub.s);wherein the value of a surface power Pn.sub.m of said progressive surface in said main meridional plane at a second point on said main meridian in a near portion of said progressive power lens is greater than the value of a surface power Pn.sub.s of said progressive surface in a plane perpendicular to said main meridional plane at said second point (Pn.sub.m >Pn.sub.s); andwherein said surface power P is defined by the following condition:P=(n-1)/r;wherein ""n"" represents the refractive index of said progressive power lens; and""r"" represents the radius of curvature at one of said first point and said second point on said main meridian in said near portion and said distance portion, respectively.