In a prospective study, the incidence of cystoid macular edema for two groups of patients was found at six weeks following surgery. The first group who underwent cataract extraction had a 50 per cent incidence. The second group who underwent elective glaucoma surgery had no patient with cystoid macular endema. At six weeks, 16 per cent of those patients who had originally developed cystoid edema, had a visual acuity of 6/12 or less, with no other cause for the poor visual result. The two major differences between these two groups of patients were the actual cataract extraction, and the presence of postoperative vitreous inflammation. No factors were noted to cause persistence of the aphakic macular edema although the technique of cataract extraction and vascular disease were implicated.