Ultra-wide field fluorescein angiography can detect the response of anti VGEF therapy such as Avastin on retinal ischemia in the setting of 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.

Inclusion Criteria:

1. Diabetic patients at age >18year with DME
2. Scheduled for Avastin therapy
3. Adequate media to obtain OCT and UWFA

Exclusion Criteria:

1. Macular pathology of any etiology
2. Preexisting systemic disease causing retinal ischemia
3. Previous laser or anti-VEGF treatment in past 3 months
4. Previous retina surgery in past 2 months
5. Allergy to fluorescein dye
6. Psychiatric disorder, Alzheimer disease and Dementia or any other disorder precluding follow-up or continuation of the study.