We reviewed the preoperative, postoperative, and follow-up examinations, fundus photographs, and fluorescein angiograms of 175 eyes of 134 patients with proliferative diabetic retinopathy treated with panretinal photocoagulation. Forty-four (25%) of these eyes lost two or more lines of vision by the time of the last follow-up examination. Follow-ups ranged from 3 to 48 months, with a median follow-up of 15 months. The most common cause of decreased visual acuity was chronic macular edema that had developed following laser treatment, occurring in 14 (8%) eyes. The causes of visual loss following panretinal photocoagulation are discussed.