PurposeTo determine the timing of neovascular regression after intravitreous injection of bevacizumab (Avastin®) 1.25 mg given as initial therapy for eyes with high-risk proliferative diabetic retinopathy (PDR) without clinically significant macular edema (CSME).Patients and methodsIn this prospective uncontrolled interventional study, eyes with high-risk PDR without CSME were treated initially with intravitreous injections of bevacizumab 1.25 mg given every 4 weeks until no neovessels were detected, followed by standard pan-retinal photocoagulation (PRP). Patients were examined 48 hours, 1, 2, and 4 weeks after each injection to determine the status of neovascularization.ResultsTwenty-one patients (24 eyes) were included in the study. Forty-eight hours after the first injection of bevacizumab, we observed complete neovascular regression in 20 (83%) eyes. Neovascular regression was maintained in the same number of eyes in the first 2 weeks. At 4 weeks, three eyes displayed neovascular recurrence, and a second injection of bevacizumab was given to the seven eyes with persistent or recurrent neovascularization. Complete neovascular regression was observed in six (86%) eyes after 48 hours and was maintained for 2 weeks following the second bevacizumab injection. Two eyes required a third injection and had complete neovascular regression when assessed after 48 hours and 4 weeks.ConclusionThe majority of neovessels completely regressed within 48 hours after intra-vitreous injection of bevacizumab given as initial therapy for high-risk PDR without CSME. The full neovascular regressive effect occurred within 48 hours and was maintained for at least 2 weeks.

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