Pars-plana Vitrectomy vs Panretinal Photocoagulation for Severe NPDR

Study eyes that receive panretinal photocoagulation (prompt PRP eyes at baseline) should have 1200 to1600 burns with a spot size on the retina of approximately 500 microns given over 1 to 3 sittings and completed within 4 weeks of initiation

Study eyes that receive standard 25G Pars-plana vitrectomy that remove all the vitreous, without laser or Silicone oil tamponade, but filled with perfusion fluid. Surgery should be completed within 4 weeks after randomization.