Safety and Efficacy of Intravitreal Ranibizumab as a Preoperative Adjunct Treatment Before Vitrectomy Surgery in Proliferative Diabetic Retinopathy (PDR) Compared to Vitrectomy Alone

Inclusion Criteria: * male or female 18 or older who have signed an informed consent * Type I or II diabetes mellitus and severe proliferative retinopathy with tractional retinal detachment, tractional-rhegmatogenous retinal detachment, tractional detachment complicated with vitreous haemorrhage or active severe proliferative retinopathy not responding to previous panretinal laser photocoagulation * study eye BCVA must have at least light perception and must not exceed 70 letters using ETDRS at testing distance 4 meters * study eye vision decrease must be resulted from severe PDR Exclusion Criteria: * Active ocular inflammation or infection * History of uveitis * Uncontrolled glaucoma * High myopia * Any concurrent intraocular condition in the study eye that in the opinion of the investigator could confound the study results * Former treatment with anti-angiogenic drugs within 30 days preceding Day 1 in the study eye * History of vitrectomy within 60 days preceding Day 1 in the study eye * History of intraocular surgery within 30 days preceding Day 1 in the study eye * Untreated diabetes mellitus * Severe hypertension (systolic pressure higher than 160mmHg) * Current use of systemic medications known to be toxic to the retina * History of thromboembolic events (incl MI and stroke) within 5 years * Major surgery within previous 3 months or planned within the next 28 days * Known coagulation abnormalities or current use of anticoagulative medications other than aspirins * Known hypersensitivity to ranibizumab or any component of it * Women of childbearing potential unless 2 methods of birth control applied * Pregnant or lactating women