COVID-19 Related Retinal Vascular Occlusion: A Systematic Review.

Background/Objectives: To provide insight into populations at higher risk of COVID-19-related retinal vascular occlusion, we identified the baseline characteristics of COVID-19 patients and vaccine recipients who developed this condition by conducting a systematic review to summarize the findings and evaluate the current knowledge on this subject. Methods: An electronic search on the PubMed and Scopus databases was performed for relevant case reports or series regarding retinal vascular occlusion in patients with past or present COVID-19 infection or SARS-CoV-2 immunization. This study was conducted using a pre-determined protocol following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: A total of 34 studies were enrolled in this systematic review. A total of 21 patients (14 males, 66.7%) have been diagnosed with COVID-19 related retinal vein occlusion (RVO, mean age = 41.9 ± 10.3 years), and 15 patients (12 males, 80%) have been diagnosed with retinal artery occlusion (RAO, mean age = 56.9 ± 13.2 years). The time to RVO since COVID-19 infection or SARS-CoV-2 immunization ranged from 8 h to 51 days (mean = 12.3 ± 15.7 days), while the time to RAO ranged from 2 to 40 days (mean = 14.9 ± 10.8 days). Fifteen out of the twenty-one patients (71.4%) with RVO had a significant improvement in visual acuity after the resolution of symptoms while eight out of the fifteen patients (53.3%) with RAO did not show improvement. Conclusions: COVID-19 seems to play a significant role in the pathogenesis of vascular occlusion, as it is suggested to increase the risk of thromboembolic episodes. However, the pathophysiologic mechanisms have not been fully elucidated, and further studies are expected to shed light on this phenomenon.