- Approximately 20% of patients undergoing cataract surgery have diabetes mellitus. To evaluate the course of diabetic retinopathy after cataract surgery. Diabetic patients with no or mild to moderate preoperative diabetic retinopathy were included and classified into 4 groups (A-D): A--The course of retinopathy, B--macular edema, C--the effect of voltaren ophtha eye drops and D--systemic glycemic control. Group E included eyes with previous laser treatment for proliferative retinopathy. Clinical and angiographic retinal findings were scored before and after surgery. Progression was defined as an increase in the retinal score. In groups A, C, D and E the non-operated eye served as a control. In group B, the eyes of nondiabetic patients who had undergone cataract surgery served as a control. Retinopathy was stable in 66% and progressed in 34% (p < 0.005). Progression occurred during the first 6 postoperative months in 84%. Preoperative retinopathy was a risk factor for progression. Good visual acuity was achieved in 67% and was correlated with: preoperative retinopathy and postoperative deterioration. Macular edema was found in 50% of eyes compared to 8% of the controls (p < 0.005). Its development was correlated with preoperative retinal status. Twenty six eyes were treated with voltaren eye drops and 24 with placebo. Progression of macular edema was seen less often in eyes treated with voltaren (p < 0.001). Deterioration of retinopathy was less common in cases when HbA1C was equal to or lower than 7.5 mg%. Close retinal follow-up after cataract surgery is recommended, especially in patients with preoperative diabetic retinopathy. Systemic control of diabetes and antiinflammatory eye drops may improve surgical results.