Progressive power ophthalmic lens

Claim 1

A progressive power ophthalmic lens comprising at least one surface contributing to an increase in refractive power from a distant portion via a progressive zone to a reading portion, the radii of curvature rh of horizontal section curves of the at least one surface contributing to the increase in refractive power and having horizontal planes where y is a constant so that a function of a distance x from a main meridian decreases in a front surface in a region of the main meridian in the distant portion and increases in the reading portion and increases in a rear surface in the distant portion and decrease in the reading portion, a course of change of curvature Δrh=rh(x,y)-rh(0,y) reversing with increasing distance x from the main meridian, the course of the change in the curvature of the horizontal section curves with increasing distance in the x direction from the main meridian being yielded by superimposing first and second functions F 1 (x,y) and F 2 (x,y), where Δrh=F(x,y)=F 1 (x,y)+F 2 (x,y), the first function F 1 (x,y) providing that the radius of curvature initially increases in the front surface or decreases in the rear surface, whereby the change in the radius of curvature reverses at a distance of 14 to 26 mm from the main meridian, the second function F 2 (x,y) providing that the radius of curvature initially decreases in the front surface or increases in the rear surface, whereby the change in the radius of curvature reverses at a distance of 14 to 26 mm from the main meridian, the absolute values of the amplitudes of the first and second functions changing in reverse along the main meridian at least in the progressive zone, and for one strip on opposite sides of the main meridian at least in the region of the distant portion a relationship is provided that .sub.δ F 2 /δx (x=x o ,Y=y o ) >δF 1 /δx (x=x o ,y=y o ), where δF 1 /δx and δF 2 /δx represents the first derivations of the functions F 1 and F 2 from x.