Retinal vein occlusion (RVO) is the second most common vascular retinal disease after diabetic retinopathy .Visual prognosis depends on the amount of retinal ischemia and macular edema. It has also been shown that the diameter of the FAZ is inversely correlated with the best corrected visual acuity. RVO can be categorized in ischemic and nonischemic vein occlusion depending on the area of non-perfusion in FA.
Fluorescein angiography (FA) remains the clinical gold standard for detecting vascular pathology in the retina. However, it is an invasive test that requires exposure to an exogenous contrast agent. Adverse effects of fluorescein range from nausea and pruritus to anaphylaxis.
Optical coherence tomography angiography (OCTA) has recently emerged as a promising noninvasive way to visualize retinal microvasculature. It uses the motion of erythrocytes illuminated with near-infrared light to generate perfusion maps. The longer wavelength avoids the potential for photochemical damage, which could be especially important for diseased retinas.