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.

Abstract: A hydrophilic polymer or copolymer is produced in an environment free from a chemical initiator and preferably by irradiation of the starting materials, particularly by gamma rays. The product polymer or copolymer is thus free from the residua of chemical initiators and the method permits the production of polymers and copolymers which are particularly suitable for use in contact with living tissue, for example as contact lenses, prosthetic devices, surgical implants, protective corneal fittings and protective membranes or bandages.