A New Patient Group in the Diabetic Retinopathy Vitrectomy Study

The Diabetic Retinopathy Vitrectomy Study (DRVS) has recently entered its second phase, a randomized trial of pars plana vitrectomy in eyes with very severe proliferative diabetic retinopathy (PDR) that still retain useful vision. Such eyes, designated group NR and characterized by severe, active, fibrovascular proliferations (see detailed eligibility requirement described later), are being randomly assigned to either of two groups, the prompt vitrectomy group or the conventional management group, in which vitrectomy is considered only if retinal detachment involving the center of the macula develops or severe vitreous hemorrhage occurs and fails to clear during six to 12 months. The rationale for vitrectomy in group NR eyes is based on clinical observations that contraction of the vitreous and fibrovascular proliferations play an important role in the evolution of PDR. Such contraction is frequently associated with vitreous hemorrhage and often leads to retinal distortion and/or detachment. Removal of epiretinal (flat) or