Preparation of cross-linked hydrogel copolymers for contact lenses

摘要

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.