Matthew D. Davis led this study because of his experience in evaluating the natural course of the disease. The study provided conclusive evidence that laser photocoagulation reduces the risk of blindness by more than 50 percent in eyes with moderately severe retinopathy; this treatment is now being used throughout the world. He and Professors of Ophthalmology Frank Meyers and George Bresnick also played leading roles in two subsequent NEI-sponsored collaborative trials evaluating treatment at earlier and later stages of retinopathy.