الفهرس 
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Abstract
SUMMARY
The most leading cause of visual loss in the working age population in developed countries is diabetic retinopathy (DR). But it is also one of the most preventable.
Twenty years after the onset of diabetes, almost all patients with type 1 diabetes and over 60% of patients with type 2 diabetes will have some degree of retinopathy, so it is essential to identify patients with retinopathy before their vision is affected.
Diabetic retinopathy occurs as a result of abnormal changes to the structure of blood vessels, which occur as a result of diabetes. In the early stages of the disease these changes affect the retina (retinopathy). The changes which occur in proliferative and non-proliferative retinopathy may also cause maculopathy. This causes diabetic maculopathy, in which changes to the retina lead to the loss of capillaries in the macula.
The severity of diabetic maculopathy can be partly established by examining the perifoveal circulation. The central macula has a foveal avascular zone (FAZ) surrounded by interconnected capillary beds. This vascular network terminates in the central macula and forms a ring at the peripheral edge of the FAZ.
DMI is an irreversible category of diabetic maculopathy, and its presence limits the potential benefits of treatments for DR.
Fluorescein angiography (FA), the gold standard for evaluating the retinal vasculature, shows both morphologic and functional changes in the blood vessels in DR. It is invasive test, provide two-dimensional image sets and localization of the depth of the lesion and size delineation of neovascularization can be difficult due to dye leakage and poor stereopsis. Another limitation is that the dyes pose risks ranging from nausea to allergic reactions, including anaphylaxis in rare instances.
Therefore a rapid non-invasive technique to visualize retinal and choroidal vessels would be beneficial.
Optical coherence tomography angiography (OCTA) is a new non-invasive imaging technique, without the use of dye, that employs motion contrast imaging to high-resolution volumetric blood flow information generating angiographic images in a matter of seconds.
Through our work on 40 eyes of 25 patients with IDM to assess accuracy of OCTA in evaluating the changes in FAZ and perifoveal intercapillary area in IDM, we found that OCTA had more delineated. In addition to its ability to detect 95% of microaneurysms detected by FA. Further researches on larger numbers would confirm these facts.