Toxic effects of high doses of monomeric methylmethacrylate were demonstrated in rabbit eyes. These effects were not related to surgical manipulation. Monomeric methylmethacrylate caused limbal hyperemia, corneal edema, corneal neovascularization, iris engorgement, anterior chamber inflammation, iris atrophy, and cataract. The doses of monomeric methylmethacrylate needed to produce these lesions were much higher than the amount of monomer available for leaching out of implanted intraocular lenses.