Abstract: A bifocal contact lens is disclosed, having a posterior surface with a base curve, and an anterior surface having a distance vision curve defining a distance vision optical zone and a near vision curve defining a near vision optical zone. A first prism component is incorporated into the base curve. A second prism component is incorporated into the distance vision curve. A process for manufacturing the bifocal contact lens by lathe cutting is also disclosed.

Abstract: A monomer for making a contact lens with improved oxygen permeability and stability is disclosed as having a first portion for increasing wettability and a second portion for increasing oxygen permeability. The first portion includes a side-chain functionality of the structural formula: ##STR1## and is hydrophilic. The second portion includes a siloxane moiety, and is usually hydrophobic.Also disclosed is a cross-linking agent, a polymeric material for making contact lenses, a method for making the polymeric material, and a method for making contact lenses from the material.

Abstract: A carrier is disclosed for supporting an optical blank in the chuck of a lathe, for machining the optical blank into a lens. The carrier has a substantially cylindrical body formed of a machinable material. The cylindrical body has an opening at a first end thereof through which an optical blank can be inserted, and a retaining portion for securing such optical blank in place. In a preferred embodiment, the retaining portion is an annular shoulder extending inwardly at a second end of the cylindrical body.

Abstract: A process for the treatment of a soft contact lens, to increase its resistance to the deposition thereon and diffusion and accumulation therein of substances which will promote its clouding and discoloration in use, and to improve its mechanical strength, includes treating a hydroxyl group-containing acrylic ester soft contact lens or replica with an organic acid anhydride for a sufficient period of time to treat at least a portion of polymer molecules on the outer surfaces, e.g. by esterifying hydroxyl groups on the molecules and facilitating extraction of organic-type impurities. The process is optionally performed in the presence of a medium which partially swells the surface regions of the lens or replica prior to or during the process.

Abstract: A contact lens for correction of astigmatism is formed from a single polymeric or copolymeric material. The lens has a central optical zone of greater rigidity than a surrounding non-optical zone. The rigidity of the central optical zone is sufficient for it to retain an astigmatism-correcting shape when worn on an eye, while the surrounding non-optical zone conforms to the shape of the eye.