 Diabetic macular edema DME is the most common cause of vision loss in diabetic retinopathy. The pathophysiology of DME is complex and multifactorial. Chronic hyperglycemia, protein kinase C PKC formation, free radical accumulation, advanced glycation end-product AGE proteins, and ischemia-driven release of vascular endothelial growth factor VEGF are some of the better understood factors that contribute to chronic retinal arterial and capillary damage and increased permeability. 