JPS54145155A - Spectacle lens - Google Patents

Abstract

PURPOSE: To obtain a spectacle lens which gives a comfortable field of view continuously from far to near vision by so forming the lens that the curvature becomes smaller in the lower region and larger in the upper region the further it goes from the main meridian.

CONSTITUTION: The lens is divided to a far vision part F, progressive focus part P and near vision part N along its main meridian MM'. At the point A, the circular intersecting line composed of the face crossing the MM' at a right angle and a refracting face exists. In the lower part of the P region and in the N region, the curvature becomes smaller the further it goes from the MM' and in the upper part of the P region and in the F region, the curvature becomes larger the further it goes from the MM' and therefore the lens of the performance of small astigmatism and distortion aberration and good total balance over the entire part of the lens may be obtained. In addition, the perpendicular components of prism are constant near the circular intersecting line perpendicularly intersecting with the main meridan MM' at the A point on the refracting face and therefore, the image with which fluctuation is difficult to sense may be obtained as against the lateral change of the eye ball.

COPYRIGHT: (C)1979,JPO&Japio