(under subclass 168) Subject matter wherein one of the multifocal lens elements has a specific prismatic correction whose prism base is located relative to the optical center of the distance and/or intermediate vision lens sections to give the desired correction.
(1) Note. The lens section with prismatic correction may be in the form of a segment fused into a lens countersink or the prismatic correction may be formed by grinding a desired area of a multifocal lens made of one piece of material.
SEE OR SEARCH THIS CLASS, SUBCLASS:
175, for prismatic-type ophthalmic lenses generally.