الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Central retinal vein occlusion (CRVO) is an important cause of visual loss among older adults throughout the world. RVO is the second most common cause of vision loss from retinal vascular disease, following diabetic retinopathy. Although Fluorescein angiography (FFA) is the gold standard in detection and evaluation of central retinal vein occlusion patients, in clinical practice it is an invasive examination with several disadvantages, notably related to dye injection and leakage, dye staining, and pooling side effects furthermore it only provides information about superficial macular capillary plexus. Recently, several OCT based angiography methods have been developed for noninvasive 3‑ dimensional vascular mapping at the microcirculation level, Optical coherence tomography angiography (OCTA) is a new non‑ invasive imaging technique that employs motion contrast imaging to high‑ resolution volumetric blood flow information generating angiographic images within seconds. This study was done on 24 eyes from 24 patients with acute central retinal vein occlusion (CRVO). Exclusion criteria included poor quality images on OCTA, previous retinal surgery, other retinal disorders such as diabetic retinopathy and cases with significant retinal hemorrhage that interfere with reliability of OCTA imaging. In addition, 20 eyes from 20 healthy persons not suffering from any ocular or systemic disease were also included as a control group. This study focused on OCTA which is a dye less noninvasive clinical diagnostic tool that performs high-resolution, 3D cross-sectional imaging of the retinal and choroid vasculature. In our study, assessment of the macula ischemia was done by detection of areas of capillary dropout as dark void areas not related to retinal hemorrhage, detection of FAZ size, VAD by OCTA and central macular thickness by conventional OCT incorporated to OCTA device. Our study revealed that eyes affected by CRVO showed larger fovea avascular zone (FAZ) as compared to the control in both superficial and deep plexuses levels and to a lower degree in the SCP than in the layer DCP. In addition, the vessel density (VAD ) in the superficial retinal vascular layer decreased as compared to the eyes of a control group of normal individuals and to a lower degree than in the deep retinal vascular layer i.e., less ischemia in superficial plexus than deep plexus. Significant increase in central macular thickness was detected in CRVO cases as compared to normal subjects and it was associated with diminished (BCVA) decimal. In the eyes with acute CRVO, OCTA demonstrated retinal vessel abnormalities such as vessel tortuosity and vessel telangiectasis. OCTA may be clinically beneficial to assess the microvascular status and treatment effects in CRVO patients.