الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Diabetic retinopathy (DR) is one of the most common and severe complications of DM and is also the leading cause of early blindness in adults. Thus, the early detection of DR is important for the preservation of useful visual acuity in later life. Fundus fluorescein angiography is considered the gold standard of diagnosis of DR, however the reported allergic reactions is a major disadvantage, especially in patients who have reported a previous episode. OCT angiography is a new convenient and noninvasive method for evaluating the microvasculature of the retina. The aim of this study is to identify the value of the optical coherence tomography angiography in evaluation of patients with diabetic retinopathy and compare the results with fluorescein angiography. All patients in this study had standard ophthalmic examination with measuring best corrected visual acuity (BCVA), anterior segment examination using slit lamp biomicroscope, fundus examination after full pupillary dilation and retinal imaging with FA using Topcon Retinal camera, and OCTA imaging using SS-OCT device (Triton, Topcon, Tokyo, Japan). The study included fifty five eyes of 30 patients having DR. Patient’s age ranged from 50 to 70 years. Sixteen patients were males and fourteen were females. The FA images of the macula were acquired, followed by quantification of the areas of the FAZs. The innermost capillaries around the fovea were identified, and the internal area was measured using ImageJ software. The number of microaneurysms was counted on the FA images within the areas corresponding to the central 3×3 mm2 areas obtained by OCTA. OCTA images of the central 3×3 mm2 were obtained, followed by measuring the areas of the FAZ (superficial and deep plexus) in them using ImageJ software. Then microaneurysms were counted in FA images and OCTA images in superficial and deep plexuses. microaneurysms appeared by OCTA as demarcated saccular or fusiform shapes of focally dilated capillary vessels in either the superficial or deep layer. The ability of OCTA to detect microaneurysms (superficial plexus) is limited compared with FA as the number of microaneurysms was more with fluorescein angiography than optical coherence tomography angiography. The number of microaneurysms was significantly larger in the deep plexus than the superficial plexus as detected by OCTA. OCTA is a new technology capable of imaging the two major retinal capillary layers, the superficial capillary plexus and deep capillary plexus without dye injection. OCTA is a promising tool for the detection and management of DR. OCTA can detect features of diabetic retinopathy. Its rapid acquisition time, the absence of need for an intravenous dye, ability to be repeated in each follow up visit, identification of small neovascular tufts and areas of capillary drop-out not obscured by leakage are some of its advantages. OCTA may be superior to FA for the early detection of DR and for the evaluation of the FAZ in DR as vascular abnormalities are more pronounced in the deep layer. OCTA has some limitations in evaluating DR, including the small field of view, and difficulty in identification of microaneurysms over a large area, inability to adequately image the peripheral retina and difficulty in imaging patients who have poor vision which causes poor fixation and image distortion. OCTA is unlikely to replace conventional FA in its current form. It could be at least complementary to FA for assessing DR in cases with contraindication to dye.