Diabetic retinopathy, including maculopathy, a major cause of blindness in working-age adults, is emerging as a major public health issue worldwide, in particular in low- and middle-income countries. Diabetic macular edema (DME), characterized by the accumulation of exudative fluid at the macula leading to macular thickening, is a common cause of sight-threatening eye disease in patients with diabetes mellitus occurring more often than proliferative DR.  Diabetic macular edema (DME) is a complication of diabetic retinopathy. It occurs when fluid builds up in the macula, the center portion of the retina. The retina is the layer of cells at the back of your eye that helps convert light into the images you see. The pathogenesis revolves around the breakdown of the blood-retinal barrier as a result of increased vascular endothelial growth factor (VEGF) and pro-inflammatory cytokine expression.  Physiologically, DME is reported to be induced by disruption of the blood-retinal barrier secondary to retinal vessel leukostasis, pericyte loss, and increased permeability of retinal pigment epithelium cells. The disruption of the blood-retinal barrier results in abnormal fluid leakage into the extracellular space and then leads to residual accumulation of fluid into the intraretinal layers. This breakdown leads to hyperpermeability and vascular leakage, ultimately resulting in DME. The Early Treatment Diabetic Retinopathy Study (ETDRS) description of the “clinically significant macular edema (CSME)” was defined by the Early Treatment Diabetic Retinopathy Study (ETDRS) in 1985 based on clinical findings and biomicroscopy. With the advances in OCT technology such as cross-sectional morphological assessment and objective quantitative thickness measurement, nearly a dozen different classification systems have been proposed.  The introduction of optical coherence tomography   made it possible to detect these morphological features of the choroid in patients with DME, such as an irregular-shaped choroidoscleral interface, focal choroidal thinning, and reduction of choriocapillaris layer thickness  Based on optical coherence tomography (OCT) images, DME is classified into six morphologic patterns: focal retinal thickening, diffuse retinal thickening, cystoid macular edema, serous retinal detachment without posterior hyaloidal traction, posterior hyaloidal traction without traction retinal detachment and posterior hyaloidal traction with traction retinal detachment. Treatment of diabetic macular edema requires compensating the set of biological and pathophysiological local and systemic changes in the eye, occurring in diabetes. Currently treatments for diabetic retinopathy include laser surgery, surgical techniques (vitrectomy), intravitreal injections of corticosteroids and anti-vascular endothelial growth factor medications. Despite the results achieved it diagnosis and treatment of diabetic macular edema, these questions require further research. 

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