Eyes responding to panretinal photocoagulation can remain stable for decades, but incomplete responses and relapses can occur in a certain percent of diabetic patients showing as proliferative diabetic retinopathy. At present vitrectomy is the main intervention for those eyes with vitreous hemorrhage, proliferative membrane, and tractional retinal detachment. And the surgical procedure might be complicated because of intraoperative bleeding. And post-operative complications might be also involved. Perioperative use of intraocular anti-VEGF might be associated with less hemorrhage related complications and better visula acuity. This study will compare intravitreal injection of anti-vascular endothelial growth factor (ranibizumab) versus sham injection one week before surgery. The investigators tried to make sure whether pre-operative injection of ranibizuman can reduce reduce intra-operative bleeding, reduce the frequency of using endodiathermy, decrease surgical time, improve microcurculation of retina, and elevte best-corrected visual acuity.
Certain percent of the eyes with proliferative diabetic retinopathymay require pars plana vitrectomy (PPV) due to vitreous haemorrhage, proliferative membrane, and tractional retinal detachment. This study will compare intravitreal injection of anti-vascular endothelial growth factor (ranibizumab) versus sham injection before vitrectomy for PDR. The main focus is to see if pre-operative injection of ranibizuman can reduce peri-operative hemorrahge related complications.