Retinal Vascular Occlusions After COVID-19 Vaccination in South Korea: A Nation-Wide Population-Based Study.

PURPOSE To investigate the association between the retinal vascular occlusion and vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS This nationwide population-based cohort study included 2,742,065 individuals aged ≥ 20 years who were vaccinated against SARS-CoV-2 from March 1, 2021, to December 31, 2021, and unvaccinated individuals matched at a ratio of approximately 1:10 by gender and age, all without a history of retinal vascular occlusion. The occurrence of retinal vascular occlusion was observed up to 60 days after the 1st vaccination date in the vaccination group, while 60 days from January 1, 2021, in the non-vaccination group. The risk of developing retinal vascular occlusion was compared between vaccinated and unvaccinated subjects. Risks were also compared among the different types of vaccines. RESULTS Vaccination lowered the risk of retinal vascular occlusion, with an odds ratio (OR) of 0.80 (95% confidence interval (CI), 0.64-0.99; p = 0.039). For individuals aged < 40 years, the vaccination lowered the risk of retinal vascular occlusion occurrence significantly compared with those over the age of 40 (OR, 0.35 for age 20-39, 0.83 for age 40-64, 0.81 for age ≥ 65; P for interaction = 0.028). There was a significant difference in the ORs for retinal vascular occlusion among the four vaccine types (p < 0.001). CONCLUSIONS SARS-CoV-2 vaccination did not increase the risk of retinal vascular occlusion. However, the risk levels differed depending on the type of vaccine used. Considering the ongoing evolution of SARS-CoV-2 vaccines, it is imperative to conduct additional assessments of the recently introduced vaccines.