Relationship Between COVID-19 and Retinal Vein Occlusions.

The relationship between coronavirus disease 2019 (COVID-19) infection or vaccination and retinal vein occlusions (RVOs) remains controversial. RVOs include central and branch RVOs. Previous studies have indicated a link between RVOs and COVID-19. RVOs develop when the retinal blood vessels are clogged by thrombin or lipid deposition. The retina, an important component of the visual apparatus, relays the visual information to the brain after light stimulation. When retinal veins are clogged, the damage can range from slightly reduced vision to complete blindness. SARS-CoV-2, the causative agent for COVID-19, leads to endothelial dysfunction and increased von Willebrand factor (VWF) antigen levels in the blood, which activate the coagulation process and platelet aggregation. Activation of tissue factors initiates the coagulation cascade, leading to fibrin formation through thrombin. Because arteries and veins sometimes cross in the retina, the vein, with its thin vessel wall, may be compressed. As a result, blood flow slows due to venous constriction, and clotting is more likely to occur at the crossing point. RVO ultimately develops through these processes. Patients with COVID-19 have significantly elevated levels of VWF antigen and activity, which likely contribute to the increased risk of thrombosis observed in COVID-19-associated coagulopathy. As RVOs align with conventional approaches, ophthalmologists should consider COVID-19 as a potential etiological factor when evaluating patients presenting with acute vision loss. Enhanced awareness of this association may facilitate timely diagnosis and tailored patient care in affected populations.