Abstract
The human retina is supplied by an extensive network of capillaries, where healthy blood flow to various parts of the retina, particularly the macula, is vital for visual functions. Any obstruction in blood flow, known as retinal vein occlusion (RVO), can reduce venous blood return. RVO can occur either at a central location (called central retinal vein occlusion [CRVO]) or a peripheral location (branch vein occlusion [BRVO]). Various techniques have been used to investigate blood flow to the retina and analyze different factors that may impact retinal blood flow. Optical coherence tomographic angiography (OCT-A) has emerged as one of the best methods, with several studies demonstrating its use to investigate changes in blood perfusion status, hemorrhage from blood vessels, and the presence of edema. Some studies have demonstrated that OCT-A is superior to other techniques.
Macular edema secondary to RVO is the most common complication that may affect visual acuity and lead to vision loss if left untreated. Several qualitative and quantitative changes caused by RVO can be detected using OCT-A, including vascular blood perfusion and vascular density. Several treatment options have been used to treat macular edema secondary to RVO and other complications. Laser photocoagulation therapy has been used extensively in the past with mixed outcomes. Glucocorticoids, especially dexamethasone (Ozurdex®), have also been used to treat macular edema secondary to RVO. Currently, anti-vascular endothelial growth factor (VEGF) agents are the gold standard for treating RVO. Ranibizumab and aflibercept are approved for the treatment of macular edema secondary to RVO, with faricimab expected to soon be approved.