<qa>  What is the most common cause of vision loss in diabetic retinopathy?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. 