Author’s Disclosure Block: Tina Felfeli, none; Yvonne M Buys, none; Sherif El-Defrawy, none; Ya-Ping Jin, none

Abstract Body
Purpose:The occurrence of conjunctivitis in patients with COVID-19 has been reported to vary largely (0-31.6%) from hospital-based studies. Using population-based data, we assessed the incidence of conjunctivitis in patients with and without COVID-19 in 2020 and in general populations pre-pandemic. Study Design: Retrospective cohort. Methods: Ontario’s physician billing data from 2010-2020 were analysed. Cohort 1: Data in 2010-2019 were used to establish the conjunctivitis incidence pre-pandemic. Cohort 2: One COVID-19 individual in 2020 was matched by age, sex and urban/rural residence to 3 randomly selected non-COVID-19 individuals in 2020 and again to 3 non-COVID-19 individuals in 2019. The 2019 matched individuals wereincluded to address the concern that people might have avoided seeking eye care during the pandemic, resulting in a “false” low conjunctivitis incidence rate among non-COVID-19 individuals in 2020.In cohort 1 and 2, conjunctivitis was the study outcome and was recognized from diagnostic codes (ICD-9 and -10) billed by all physicians. In cohort 2, COVID-19 infection was the exposure and was identified using the lab confirmed COVID-19 test result from Jan 15 to Nov 30, 2020. The adjusted hazard ratio (aHR) derived from the Cox regression model was used to assess the association between COVID-19 infection and conjunctivitis risk. Variables adjusted for included age, sex, rural/urban residence, neighborhood income level, diabetes, cancer, hospitalization and ICU stay. Results: Pre-pandemic, the annual incidence of conjunctivitis varied slightly from 2.71% in 2010 to 2.16% in 2019. Higher rate was observed in people aged 0-19 (3.11%) vs other age groups (1.56-1.97% in 2019) and in females (2.28%) vs males (1.89% in 2019).In 2020, 106,713 individuals had lab-confirmed COVID-19 infection, with a mean age of 43.7 (ranging from 0-100) years and 52% females. Conjunctivitis occurred in 200 of them within 4 weeks of COVID-19 onset. The conjunctivitis incidence was 0.19% per 4 person-weeks (or 2.5% per year) in COVID-19 individuals, higher than the incidence in non-COVID-19 individuals (0.11% per 4 person-weeks, or 1.4% per year) in 2020. The aHR of conjunctivitis was 1.6 (95% confidence interval [CI] 1.4-2.0), significantly higher in individuals with vs without COVID-19.However, compared with the matched non-COVID-19 individuals selected from 2019, the conjunctivitis incidence in COVID-19 individuals was not higher: 0.19% vs 0.19% per 4 person-weeks for individuals with and without COVID-19. The aHR of conjunctivitis was 0.9 (95% CI 0.8-1.1) for individuals with vs without COVID-19. Conclusions: The risk of conjunctivitis was significantly higher in individuals with COVID-19 vs non-COVID-19 individuals selected from the pandemic period. However, this increased risk was not observed compared with non-COVID-19 individualschosen from the pre-pandemic period.