Progressive ophthalmic lens

摘要

A progressive ophthalmic lens with a continuous progressive surface comprises a substantially constant power first area matched to far vision. It also has a substantially constant power second area matched to near vision. Between the first and second areas is a progressively varying power third area. This is defined by a central part extending to both sides of the main progression meridian. In this central area each line on the progressive surface parallel to the main progression meridian substantially satisfies at every point the following equation: 1/R1-1/R2=constant wherein R1 and R2 are the principal radii of the surface at the point concerned.