Changes in the incidence of optic neuritis before and after COVID-19: A nationwide study 2017-2022.

ABSTRACT

PURPOSE: To determine the risk of optic neuritis (ON) during non-pharmaceutical interventions (NPI), vaccination and infection phase of coronavirus disease-19 (COVID-19) in comparison to pre-outbreak levels in pediatric and adult populations in South Korea. DESIGN: A nationwide, population-based, retrospective study. PARTICIPANTS: South Korean individuals with a primary diagnosis of ON between January 2017 and December 2022. METHODS: The Korean Health Insurance Review and Assessment database was queried for new diagnoses of ON between January 2017 and December 2022. Data were divided into 4 periods pre-COVID-19 (2017-2019), NPI (2020), nationwide vaccination (2021) and nationwide infection (2022). The risk of ON development for each period was calculated and compared to pre-COVID-19 levels with 95% confidence intervals (CI) reported. MAIN OUTCOME MEASURES: Incidence rate ratio (IRR) of ON for each period. RESULTS: A total of 7,216 patients (52.7 % females) were included in the study, with 3,770 patients diagnosed with ON pre-COVID-19 (2017-2019), 1,193 patients during NPI, 1,135 patients during the vaccination and 1,118 patients during the infection phases. The annual incidence of ON during NPI (IRR 0.92 (95% CI 0.85-1.00), P=0.043), vaccination (IRR 0.88 (95% CI 0.81-0.95), P=0.001) and infection (IRR 0.86 (95% CI 0.80-0.93), P<0.001) phases significantly decreased compared to pre-COVID-19 levels when adjusted for age and sex. The proportions of diagnosis with multiple sclerosis (MS), neuromyelitis optica (NMO), and acute disseminated encephalomyelitis (ADEM) among patients who developed ON significantly increased in 2021 in comparison to the pre-outbreak levels (9.87% vs. 5.81%; P=0.0002). CONCLUSIONS: The risks of ON development during NPI, vaccination and infection phases of COVID-19 did not increase in comparison to the pre-outbreak levels in general population. However, COVID-19 vaccination may be associated with increased risks of ON associated with diseases such as ADEM, MS and NMOSD.