JPS54104853A - Spectacle lens - Google Patents

Abstract

PURPOSE: To provide a comfortable field of view continuously from far vision to near vision to presbyopes by dividing the lens to upper and lower areas with the circular line of intersection that the face crossing at a right angle to the main meridian and a refractive face assume in the bottom end or lower part of a progressive zone thereby changing curvatures.

CONSTITUTION: A far vision part F, intermediate progressive zone P, near vision part N from above are provided along the main meridian MM' in the central longitudinal direction and the main meridian MM' is umbilical point form over the entire line, creating sharp images. There is a circular line of intersection that the face crossing at a right angle to the main meridian MM' and a refractive face assume in the bottom end or in the part lower than this of the progressive zone P to divide the lens in upper and lower areas and change its curavatures, thereby enabling a wide field of view to be obtained from the progressive focal point to far vision part F and enabling astigmatism and distortion aderrations to be kept minimum at the periphery of the near vision part N. In addition, the umbilical form of the main meridian MM' gives a comfortable field of view along the main meridian.

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