PRP vs Bevacizumab for PDR Treatment

Inclusion Criteria: * Age \>= 18 years * Diagnosis of diabetes mellitus (type 1 or type 2) * Presence of PDR which the investigator intends to manage with PRP alone but for which PRP can be deferred for at least 4 weeks in the setting of intravitreal Bevacizumab , in the investigator's judgment. * Best corrected Snellen equivalent 20/320 or higher on the day of randomization. * Media clarity, pupillary dilation, and study participant cooperation sufficient to administer PRP and obtain adequate fundus photographs and OCT. Exclusion Criteria: * Significant renal disease, defined as a history of chronic renal failure requiring dialysis or kidney transplant. * Myocardial infarction, other acute cardiac event requiring hospitalization, stroke, transient ischemic attack, or treatment for acute congestive heart failure within 4 months prior to randomization * Systemic anti-VEGF or pro-VEGF treatment within 4 months prior to randomization. * For women of child-bearing potential: pregnant or lactating or intending to become pregnant within the next 3 years. * Tractional retinal detachment involving the macula. -- A tractional retinal detachment is not an exclusion if it is outside of the posterior pole (not threatening the macula) and in the investigator's judgment, is not a contraindication to intravitreal Bevacizumab treatment and also does not preclude deferring PRP for at least 4 weeks in the setting of intravitreal Bevacizumab * Macular edema is present that is considered to be related to ocular surgery such as cataract extraction orclinical exam and/or OCT suggest that vitreoretinal interface abnormalities disease (e.g., a taut posterior hyaloid or epiretinal membrane) is the primary cause of any macular edema. * An ocular condition is present (other than diabetic retinopathy) that, in the opinion of the investigator, might alter visual acuity during the course of the study (e.g., retinal vein or artery occlusion, uveitis or other ocular inflammatory disease, neovascular glaucoma, * Substantial cataract that, in the opinion of the investigator, is likely to be decreasing visual acuity by 3 lines or more (i.e., cataract would be reducing acuity to 20/40 or worse if eye were otherwise normal). * History of intravitreal anti-VEGF treatment at any time in the past 2 months. * History of corticosteroid treatment (intravitreal ) at any time in the past 4 months. * History of major ocular surgery (including vitrectomy, cataract extraction, scleral buckle, any intraocular surgery, etc.) within prior 4 months or anticipated within the next 6 months following randomization. * Exam evidence of severe external ocular infection, including conjunctivitis, chalazion, or substantial blepharitis * Uncontrolled glaucoma (in investigator's judgment). * Aphakia