Diabetes mellitus is associated with long-term complications of macro vascular and micro vascular including Retinopathy, neuropathy, and nephropathy. Diabetic affects the retina's neurovascular component. Two main classes of DR: non-proliferative DR (NPDR) in addition to proliferative stages: no DR, mild, moderate, severe, and proliferate DR (PDR).
Diabetic macular edema is accumulation of plasma leaked in the extracellular space in macula. It is a chronic progressive retinal disorder that results in long-lasting complete blindness. Nowadays it is classified into centrally involving and non-centrally involving. The gold standard treatment now is anti-VEGF.
The choroid is a dense vascularized structure. It supplies oxygen and nutrients to retina's outer layers (ORL) and RPE, controls posterior portion of the eye's temperature, and removes waste products from outer retina. Normal SFCT range from 191.5 ± 74.2 to 354 ± 111 μ. I tis divided to5 sublayers in order from inside to outside: Bruch's membrane, (CC), Haller's and Sattler's, and suprachoroidal space. Diabetic patients without diabetic retinopathy have thicker choroid. However, a general thinning of choroid is observed on EDI-OCT with DR. Choroid was evaluated using laser Doppler flowmetry, indocyanine green angiography (ICGA), and ultrasonography in vivo, or in vitro using histological analysis. Nowadays the enhanced depth imaging optical coherent tomography (EDI-OCT) and Optical coherence tomography angiography (OCTA) are the gold standard in imaging of choroid.