The Effect of Bevacizumab on Peripheral Retinal Changes as Imaged by Wide -Field Fluorescein Angiography in Diabetic Macular Edema

The major causes of vision loss in diabetic retinopathy are diabetic macular edema (DME) characterized by thickening of the macula due to abnormal leakage of the retinal vasculature. Ischaemic changes and microvascular pathologies have long been hypothesized to play a role in the development of DME. In diabetic retinopathy, ischaemia stimulates the production of vascular endothelial growth factor (VEGF), which can lead to the breakdown of blood-retinal barriers, and may cause DME through an increase in retinal vessel permeability. DME is best evaluated by optical coherence tomography (OCT) while retinal ischemia is determined by Fluorescein angiography. With the avaiability of ultra wide field fluorescein angiography, the investigators can now accurately measure the degree of ischemia in peripheral retina. Thus, this study will provide us data on the degree of retinal ischemia in nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR) cases as well as the measurable change that occurs in retinal ischemia after intra vitreal injection of bevacizumab.