During the period January 1987 till December 1990 192 patients (204 eyes) underwent pars plana vitrectomy (PPV) with silicone oil internal tamponade. 141 eyes were phakic and 63 eyes aphakic. 65 of the phakic eyes were diabetic, and 76 eyes nondiabetic. The silicone oil was removed on average at 8.3 months postoperatively. Cataract developed faster in the nondiabetic group and in the eyes with partially detached retinas. In all cases there was a direct contact between the posterior capsule and silicone bubble. Extracapsular cataract extraction (ECCE) was done in 75 eyes. In 59 eyes intracapsular cataract extraction (ICCE) was performed and in 7 eyes pars plana lensectomy (PPL). Histologically proliferation and metaplasia of the lens epithelium was observed. Clinical and histological findings suggested that the silicone cataract formation was malnutritional due to inhibition of lens metabolism (anaerobic glycolysis).