| abstract |
A hydrophilic copolymer suitable for contact lenses comprises units derived from acrylic acid or methacrylic acid or from a hydrophilic monomer, such as N-vinyl 2-pyrrolidone or 4-vinyl pyridine, containing at least one heterocyclic group as a major hydrophilic unit. The copolymer preferably contains units derived from a hydrophobic monomer, such as methyl methacrylate, and it may also contain units derived from a crosslinking agent and an ethylene oxide-propylene oxide block copolymer. The copolymers are capable of absorbing large quantities of water and are particularly suitable for use in contact with living tissue. |