Progressive multifocal ophthalmic lenses

摘要

Ophthalmic lenses wherein the curvature of the refractive surface changes along the principal meridian between the optical center of a far vision viewing zone and the optical center of a near vision viewing zone in accordance with a predetermined law is provided. The refractive surfaces of the lenses are divided into a far vision viewing zone, an intermediate vision viewing zone and a near vision viewing zone by a curve which intersects the principal meridian curve at the optical center of the far vision viewing zone and a second curve which intersects the principal meridian curve at the optical center of the near vision viewing zone. An angle made by a line normal to the refractive surface from each point of an intersection of an arbitrary plane which is parallel to a plane including the principal meridian curve and the refractive surface of the lens and a plane including the principal meridian curve is constant in the far vision viewing zone and in the near vision viewing zone. The angle changes in accordance with the same law as that of the curvature of the refractive surface between the optical center of the far vision viewing zone and the optical center of the near vision viewing zone along the principal meridian curve in the intermediate vision viewing zone.