Presbyopic contact lens

Claim 1

A contact lens for correction of presbyopia having a generally spherical anterior surface; and a posterior side including an annular spherical surface which is an outer residual portion of a spherical base curve generally matched in radius of curvature to a portion of the cornea over which said spherical surface lies and a central generated aspherical surface extending from the center of said posterior side substantially beyond the diameter of the pupil, said generated surface being generated into said base curve by a continuous operation beginning at the center of the original base curve removing continuously less material from the center outward, said generated surface having a central portion which optically cooperates with said anterior surface to provide an appropriate diopter correction for distance vision; and a paracentral portion of said generated aspherical surface around said central portion having progressively increasing radii of curvature and decreasing eccentricities away from the center, said paracentral portion cooperating with said anterior surface to provide a gradient of appropriate diopter add for close-in and intermediate viewing; said annular spherical surface and a portion of said generated polished surface beyond said paracentral portion fitting closely adjacent the cornea.