Abstract: A bifocal contact lens has a distant-vision portion of a diameter between 3 and 5 mm either located in the center of the lens or offset about 2 mm above the center. The anterior surface of the lens is cast in an injection molding machine from a working die which itself is made from a master-die composed of two pieces of steel, a plug portion being tightly fitted in an aperture in the carrier portion so that the boundary of the different prescription curvatures of the plug and carrier portion will meet as closely as possible. The plug portion is shrink-fit inside the carrier portion. No further finishing procedures are necessary after casting the bifocal lens in one piece from the working dies, and the working dies are so cheap to cast that they may be melted down after one or a few uses to make new working dies from the steel master-dies.

Abstract: A composition which is hydrophobic but possesses excellent wettability comprising copolymers and terpolymers of a polysiloxane and esters of acrylic and methacrylic acids. These compositions are suitable for use as ocular membranes worn in contact with the eye which possess excellent oxygen permeability, light transmission, wettability, mucophobicity, and lipophobicity and which can be worn for extremely long periods of time and then disposed of.A method of preparing the ocular membranes is disclosed, in which the composition is place between disposable molds and cured therein. The cured, mechanically and optically finished ocular membranes are recovered by the destruction of said molds and without secondary operations.The ocular membrane is a flexible, oxygen-permeable, membrane, adapted to be inserted on the eye and worn thereon continuously for extended periods.