Diabetic macular edema (DME) can cause structural retinal changes severe enough to make it the most common cause of visual loss in patients with diabetes. DME is defined by retinal thickening involving or threatening the center of the macula, secondary to the intraretinal accumulation of fluid in the macular area. Although the pathogenesis of DME is still not fully understood, it is mainly caused by the breakdown of the inner blood–retinal barrier. DME can develop at all stages of diabetic retinopathy (DR), but appears to occur more frequently as the severity of DR increases. Risk factors for DME include duration of diabetes, poor glycemic control, hypertension, proteinuria, and hypercholesterolemia. Combined with laser photocoagulation, therapy is therefore directed at controlling these factors. However, other therapies directed at the causative mechanisms of DME are currently being investigated in …