Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus (DM), while proliferative diabetic retinopathy (PDR) is the principal cause of severe visual loss in patients with diabetes. Since 1981, Panretinal photocoagulation (PRP) has been a standard of treatment for PDR. However, PRP can be associated with adverse effects, including visual field constriction, decreased night vision, and worsening of coexisting diabetic macular edema (DME). For this reason, some authors have advocated targeted treatment with PRP. Targeted retinal laser photocoagulation (TRP) is designed to treat areas of retinal capillary non-perfusion and intermediate retinal ischemic zones in PDR that may spare better-perfused tissue from laser-induced tissue scarring. Protocol S by Diabetic Retinopathy Clinical Research Network (DRCR.net) has shown that patients that receive ranibizumab as anti-vascular endothelial growth factor (anti-VEGF) therapy with deferred PRP are non-inferior regarding improving in visual acuity to those eyes receiving standard prompt PRP therapy for the treatment of PDR. Retinal ischemia is an important factor in the progression and prognosis of diabetic retinopathy. Regarding the effect of anti-VEGF drugs on macular perfusion, several studies have shown mixed results with an increase, decrease, or no effect on perfusion in response to anti-VEGF treatment. In many of these studies, however, patients with more ischemic retinas were not included. Fluorescein angiography (FA) was the method used to assess changes in macular perfusion after anti-VEGF injections in most of the clinical trials. Despite its clinical usefulness, however, FA is known to have documented risks. Optical coherence tomography angiography (OCTA) in macular perfusion evaluation in these cases was recommended by some investigators. Several studies have proved the reliability of OCTA in detecting and quantifying macular ischemia in diabetics. The investigators aim to compare changes in the macular perfusion in patients with PDR after treatment with anti-VEGF therapy versus TRP versus Standard PRP using OCTA.
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Change in foveal avascular zone area
Timeframe: 0, 3, 6, 9, and 12 months
Change in vascular density of the retinal capillary plexuses
Timeframe: 0, 3, 6, 9, and 12 months