Abstract: An ophthalmic lens is described having a front face which is a surface of revolution and is located entirely in front of the transverse plane tangential to its center. The curve representing the half-meridian of this front face corresponds to the following general formula:x=ay.sup.2 +by.sup..alpha. +cy.sup..gamma.in which the coefficient a is different from zero and negative, at least one of the coefficients b and c is different from zero and positive, .alpha. is a real number which is greater than or equal to 3 and less than 4, and .gamma. is a real number which is greater than or equal to 4.

Abstract: A molding assembly for casting soft contact lenses especially such lenses formed of hydrophobic material. Such a molding assembly comprises a molding cavity defined by the dies of the assembly and an annular gasket or sealing member joining the peripheries thereof. The perimeter of largest diameter of the molding cavity is defined by contact between a sealing ridge which is part of the concave die or the gasket or sealing member and a bearing surface which is part of the other of the concave die or the gasket or sealing member.The annular gasket or sealing member may have an annular skirt adapted to embrace the concave die in the closed position of the assembly.The gasket or sealing member is carried by the convex die and may be integrally formed in one piece with the convex mold.

Abstract: Two metallic half-moulds are produced from a prototype. The half-moulds have complementary mould faces which abut when the mould is closed, and moulding surfaces formed with annular rim depressions joined by a bridge cavity, each rim depression bordering a support surface for a false lens. A webbed frame front is moulded, false lenses are cut from that moulded front, and the mould faces which abut are set-back by a total amount corresponding to the shrinkage of the false lenses, so that the false lenses are gripped between the support surfaces and shape lens bezels in the rims when a frame front is moulded.

Abstract: An improved flexible contact lens is provided having hydrophilic and lipophobic properties which allow extended duration of wear by eliminating or greatly reducing the risk of rupture of the natural tear film produced by the cornea. These properties are achieved by crosslinking a selected water soluble polymer which has been grafted onto a pre-formed substrate, for example crosslinking polyvinyl pyrrolidone which has been previously grafted onto a silicone substrate. The grafting and the crosslinking are accomplished in separate stages.

Abstract: A copying machine which can reproduce convex or concave surfaces having smaller radii of curvature at the edge than at the center, for example the surfaces of moulds for making contact lenses, has a cam assembly including a cam with a part-cylindrical cam surface mounted on a base. The cam has a part-circular section in the plane perpendicular to the cam surface generatrices and a straight section tangential to and continuous with one end of the part-circular section. The latter is slidably mounted on a concentric part-circular guide on the base, allowing rotary movement about its geometric center. The guide and at least the part-circular section of the cam have complementary square profiles. The part-circular cam section may be locked in position on the guide by screws threaded into the guide and passing through a concentric part-circular slot in the cam.

Abstract: An improved flexible contact lens is provided having hydrophilic and lipophobic properties which allow extended duration of wear by eliminating or greatly reducing the risk of rupture of the natural tear film produced by the cornea. These properties are achieved by crosslinking a selected water soluble polymer which has been grafted onto a pre-formed substrate, for example crosslinking polyvinyl pyrrolidone which has been previously grafted onto a silicone substrate. The grafting and the crosslinking are accomplished in separate stages.