Preparation of hydrogel for soft contact lens with water displaceable boric acid ester
AssigneeMia Lens Production A/S
InventorHans-Ole Larsen
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Abstract
Soft contact lenses are made by polymerizing a substantially anhydrous polymerization mixture containing a polymerizable acrylic or methacrylic monomer, and a water displaceable ester of boric acid and a compound containing 3 or more hydroxyl groups so as to form a hydrophilic polymer containing at least 30% of said boric acid ester. In a preferred embodiment, the polymerizable is effected in a mould cavity where the contact between a sharp circular edge in one mould part and a spherical surface in the other mould part defines the edge of the lens and the distance between the two mould surfaces outside the sharp edge increases in all radial directions away from the center.
Claims13
A method of forming a hydrogel of improved mechanical and optical properties appropriate for use in a soft contact lens which comprises providing a substantially anhydrous polymerizable mixture of a polymerizable, hydrophilic hydroxy ester of acrylic or methacrylic acid and a polyhydric alcohol, and a water displaceable ester of boric acid and a polyhydroxyl compound having at least 3 hydroxyl groups or mixtures thereof, causing said mixtures to polymerize so as to form a hydrophilic polymer containing at least 30% by volume of said boric acid ester, and displacing said boric acid ester with water.
Dependencies are inferred from the claim text.