Two randomized trials were carried out in the DRVS among patients ages 18 to 70 years who had either insulin-dependent or non-insulin-dependent diabetes. In the first trial, the 616 patients who were recruited had severe visual loss from recent severe vitreous hemorrhage in at least one eye. Eligible eyes were randomly assigned either to early vitrectomy or to conventional management. In the conventional management group, vitrectomy was carried out 1 year later if hemorrhage persisted; vitrectomy was carried out sooner if retinal detachment -involving the center of the macula occurred.