PRP vs PRP+IVC for Severe nPDR

Inclusion Criteria: Type II diabetic patients, 18 years and older, were included if the participants had: 1. severe non-PDR in either eyes with/without diabetic macular edema; 2. ETDRS letters-measured best-corrected visual acuity (BCVA) ranging from 20/40 to 20/320 Snellen equivalent; 3. no previous treatment (of any type) in either eye. Exclusion Criteria: 1. history of prior laser treatment or vitrectomy in the study eye; 2. history of thromboembolic event - including myocardial infarction or cerebral vascular accident; 3. major surgery within the prior 6 months or planned within the next 28 days; 4. history of glaucoma or ocular hypertension; 5. loss of vision as a result of other causes; 6. history of systemic corticosteroid therapy within the last 3 months; 7. severe systemic disease other than diabetes mellitus; 8. known coagulation abnormalities or current use of anticoagulative medication other than aspirin 9. any condition that could affect followup or documentation (including preretinal or vitreous hemorrhage).