Reports of changes in contrast sensitivity in proliferative diabetic retinopathy (PDR) patients after panretinal photocoagulation (PRP) have considered only relatively short-term results, and these have been conflicting. We evaluated contrast sensitivity changes in 30 eyes of 29 PDR patients after PRP. The patients were divided into two groups. One, group A, received PRP at one sitting, and the other, group B, at two sittings. Before and at regular intervals after PRP, all of the patients underwent a battery of macular function tests for best-corrected visual acuity, color vision, contrast sensitivity, and photostress. Contrast sensitivity was significantly affected (P < .001) in both groups immediately after PRP, but stabilized to prelaser levels by the end of 3 months. Color-vision-error scores also were significantly higher (P < .001) immediately after PRP. Best-corrected Snellen visual acuity, however, remained stable at prelaser levels. Contrast sensitivity appears to provide a more sensitive measurement of visual acuity than the Snellen chart for monitoring foveal integrity in patients undergoing PRP.