Severe Vision Impairment and Its Association with COVID-19 Susceptibility, Severity, and Mortality: A Population-Based Cohort Study.

Background/Objectives: We investigated the associations of severe vision impairment (SVI) with SARS-CoV-2 infection and COVID-19 outcomes using the nationwide K-COV-N database, which links Korea Disease Control and Prevention Agency SARS-CoV-2 testing records with National Health Insurance Service data. Methods: Adults aged ≥20 years with laboratory-confirmed SARS-CoV-2 infection and matched controls who either tested negative or were untested but had no documented SARS-CoV-2 infection between 8 October 2020, and 31 December 2021, were included. Pre-existing SVI was defined using an inclusive algorithm based on either a best-corrected visual acuity <6/60 in the better-seeing eye in the health-checkup database or legal SVI recorded in the National Disability Registration System before the COVID-19 observation period. Propensity score matching (1:30) was used to evaluate SARS-CoV-2 test positivity in the overall cohort and severe COVID-19 outcomes among infected individuals. Results: The study included 560,182 SARS-CoV-2-positive individuals and 1,677,364 matched controls. After adjustment, SVI was associated with a trend toward higher SARS-CoV-2 test positivity (adjusted odds ratio [aOR], 1.09; 95% confidence interval [CI], 0.99-1.20). Among infected individuals, SVI was associated with increased odds of severe COVID-19 illness (aOR, 3.05; 95% CI, 2.59-3.58) and COVID-19-related death (aOR, 1.39; 95% CI, 1.13-1.71), with stronger associations during the Delta variant period. Conclusions: These findings suggest that SVI is associated with poorer COVID-19 outcomes and may increase susceptibility to SARS-CoV-2 infection.