Abstract This specification discloses a method of making a contact lens blank including the steps of grinding a circular substrate to form a curved surface on a face thereof, forming a plastic mold with a curved surface complemental to that of the substrate and a pair of through passages opening onto its curved surface and of a desired cross-section, inserting a segment of a plastic material having one index of refraction different to that of said substrate and having a cross-section corresponding to that of said passage in each of said passages, clamping said mold to said substrate, bonding said segments to the curved surface of the substrate by heat and fusion, removing said mold from the substrate and segments, and restoring its original shape to the substrate by applying thereto a plastic having an index of refraction different from that of the substrate and segments. Methods having alternative steps are also disclosed.
The method of claim 1 together with the additional steps of cutting a contact lens out of said blank, said contact lens having anterior and posterior lens surfaces of cooperating radii of curvature to provide coinciding optical centers in all powers of the lens, and polishing said lens surfaces.
Claim 2
Dependent Claim
296 words
In the making of a blank for a multifocal contact lens, said blank including a substrate having a curved interface and a pair of optically smooth segments, each of said segments presenting a ledge interface of substantial thickness where said segments meet a lens surface to be cut and polished, the method comprising the steps of: a. cutting and polishing a curved interface on a substrate of polymethacrylate having a selected index of refraction, said curved surface having at least one radius of curvature; b. forming a mold of polytetrafluorethylene with a curved surface complemental to said interface and a pair of through passages opening onto said curved surface; c. casting a segment of a soluble pitch in each of said passages, said segments having cross-sections corresponding to those of said passages in which they are cast and end surfaces at the curved mold surface; d. clamping said mold with the segments therein to said substrate with the curved surface of the mold and the ends of the segments engaging the interface of the substrate; e. bonding said segments to said substrate by heat and fusion; f. removing said mold from said substrate leaving the segments bonded to the substrate; g. restoring the original shape and dimensions of said substrate by casting thereon a plastic monomer having an index of refraction different from that of said substrate; h. dissolving sand removing said segments of pitch to create voids; and i. casting a plastic polyester having an index of refraction different from those of said substrate and plastic monomer in said voids; whereby the plastic polyester which replaces the segments of soluble pitch presents ledge interfaces of substantial thickness at points where ledge interfaces will meet a lens surface to be cut from said blank and polished.
Claim 3
Dependent Claim
49 words
The method of claim 3 together with the additional steps of cutting a contact lens out of said blank, said contact lens having anterior and posterior lens surfaces of cooperating radii of curvature to provide coinciding optical centers in all powers of the lens, and polishing said lens surfaces.