JPS5492338A - Spectacle lens - Google Patents

Abstract

PURPOSE: To provide continuously comfortable fields of view from far vision to near vision to presbyope by so forming the lens that curvatures become smaller as it goes further from the main meridian in the lower region of the group of lines of intersections that the face perpendicular to the main meridian assumes and the curvatures increase in the upper region.

CONSTITUTION: The lens is divided to far vision part F, progressive focus P and near-vision part N along the main meridian MM' and at the point A the circular lines of intersections composed of the face crossing at a right angle to MM' and a refractive face exist. In the N and P regions, curvatures become smaller as it goes away from the main meridian MM' and therefore astigmatisms and distortion aberrations may be minimized in the peripheral part of the lens. In the F region, the curvatures increase as it goes away from the main meridian MM' and therefore the distortions of the entire part of the lens may be minimized. The neighborhood of the cicular lines of intersections perpendicularly intersecting with the main meridian MM' at the point A is umbilical point form, where the sharp images may be obtained as against the right and left changes of the eye balls.

COPYRIGHT: (C)1979,JPO&Japio