Polyvinyl alcohol derivatives containing pendant (meth)acryloyl units bound through urethane groups and crosslinked hydrogel contact lenses made therefrom

Claim 1

A hydrated contact lens prepared by crosslinking a polymer in the presence of an organic solvent and a free radical initiator, in a contact lens mold, and equilibrating the resultant swollen crosslinked polymeric material in an aqueous medium to recover said hydrated contact lens, wherein said polymer is an organic aprotic solvent soluble polymer which is a derivative of a polyvinyl alcohol having a weight average molecular weight of at least about 2,000, containing an effective amount between about 0.5 to about 20 percent, based on the number of hydroxyl groups on said polyvinyl alcohol, of units of the formula ##STR9## wherein R 1 and R 2 are independently straight or branched chain alkylene of 2 to 8 carbon atoms, arylene of 6 to 12 carbon atoms, a saturated cycloaliphatic divalent group of 6 to 10 carbon atoms, aralkylene of 7 to 14 carbon atoms, or aralkarylene of 13 to 16 carbon atoms; n is 0 or 1; A 1 is ##STR10## where R' is hydrogen or lower alkyl; A is --O--, --NH-- or ##STR11## where R" is hydrogen or lower alkyl; R 3 is hydrogen or methyl; and R 4 is hydrogen, methyl or --COOR 5 where R 5 is hydrogen or lower alkyl with the proviso that when R 3 is methyl then R 4 is hydrogen.