In this randomized 3-armed clinical trial, 105 eyes with PDR will be included and divided randomly into 3 groups: IVB group (35 eyes) that receive 4 monthly IVB injections and then rescue IVB, PRP group (35 eyes) that undergo full PRP in 2 or 3 sessions and then rescue IVB, and combination group (35 eyes) that receive 2 bimonthly IVB injections and a modified laser (1 session anterior to the equator) and then rescue IVB or laser. Diabetic macular edema (DME) will be treated independently in all groups by IVB. Primary outcome will be the number and activity of neovascularizations at 4,8 and 12 months and secondary measures will be changes in best corrected visual acuity (BCVA) and central macular thickness (CMT), and number of examinations and injection.

Inclusion Criteria:

• Presence of PDR with the indication of full PRP according the intend of investigator
• Best corrected visual acuity of 20/320 or better
• Media clarity, pupillary dilation and patient's cooperation sufficient for full PRP, wide-field FAG and OCT

Exclusion Criteria:

• History of prior PRP with more than 100 burns outside the posterior pole
• Tractional retinal detachment involving the macula
• Evidence of neoplasia of angle on examination
• Macular edema due to a cause other than DME
• Any ocular condition which may change visual acuity during the study
• Substantial cataract which has declined the vision by 3 lines or more
• History of intravitreal injection of anti-VEGF agent in past 2 months
• History of any use of corticosteroid during past 4 months
• History of major intra-ocular surgery except cataract surgery
• History of YAG laser capsulotomy during past 2 months
• Aphakia and uncontrolled glaucoma according to investigator judgment