Two original Ridley intraocular lenses, made of poly(methyl methacrylate) (PMMA) at least 35 years ago, were extracted in two different media, diethyl ether and water. The extracts were suitably processed and analyzed by high resolution capillary gas chromatography. Residual monomer (MMA) was detected in both extracts. The amount of MMA in the aqueous extract was significantly lower than that in the ether extract. It is postulated that the residual monomer in lenses originated from an incomplete polymerization at the time of the polymer production. However, the MMA content found in one lens (0.147%) is comparable to that currently detected in modern IOLs, and probably does not cause toxic reaction in the eye because it is leached out by aqueous fluid action to a very low extent.