2-Hydroxyethyl methacrylate polymer with methacrylic acid 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, polymer with 2-methyl-2-propenoic acid 2-Propenoic acid, 2-methyl-, polymer with 2-hydroxyethyl 2-methyl-2-propenoate 31693-08-0 FRE-FLEX Focofilcon A Focofilcon A [USAN] Poly(hydroxyethyl methacrylate-methacrylic acid)hydrogel