Cross-linked hydrogel copolymers for contact lenses
AssigneeGlobal Vision (U.K.) Limited
InventorsIvor B. Atkinson, Barry C. Holdstock
Life of this patent
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Abstract
The invention relates to soft contact lenses having a water content of at least about 45% and comprising a hydrated copolymer of a major proportion of an hydroxyalkyl acrylate or methacrylate, up to 12% by weight of an ethylenically unsaturated acid or anhydride, a minor proportion of a cross-linking monomer and a minor proportion of styrene or a substituted styrene, the free acid or anhydride groups being in salt form.
Claims6
A soft contact lens having a water content of at least about 30% by weight based on the weight of the hydrated lens, said lens being characterized by a high tensile strength and composed of a hydrated copolymer comprising units from a major proportion of an hydroxyalkyl acrylate or methacrylate, up to 12% by weight of an ethylenically unsaturated acid or anhydride based on the total weight of comonomers, a minor proportion of a cross-linking monomer, and from about 4 to about 30% by weight of styrene or a substituted styrene, with free acid or anhydride groups in the copolymer being in salt form.
A contact lens which comprises a hydrated, sparingly cross-linked copolymer of a major proportion of an hydroxyalkyl acrylate or methacrylate, up to 12% by weight of an ethylenically unsaturated carboxylic acid or anhydride, up to about 5% of a cross-linking monomer and from about 4 to about 30% of styrene or substituted styrene, at least some of the carboxylic acid or anhydride groups in the copolymer being in salt form, the percentages of each comonomer being calculated by weight of the total weight of comonomers.
Dependencies are inferred from the claim text.