Four patients with diabetes mellitus had cataract extraction with implantation of a hydrophilic acrylic intraocular lens (IOL) (ACRL-C160, Ophthalmed). The IOLs showed progressive and generalized opacification 10 to 20 months after implantation, decreasing visual acuity. All 4 IOLs were removed. By light microscopic examination, the IOL surfaces were wrinkled and encrusted with microspheres. Electron microscopy revealed the material to be crystalline in nature. Energy dispersive x-ray spectrum analysis showed that the deposits were mainly composed of calcium and phosphate.