Changes in the Incidence of Optic Neuritis before and after the Coronavirus Disease 2019 Outbreak: A Nationwide Study 2017-2022

Abstract

Purpose: To determine the risk of optic neuritis (ON) during nonpharmaceutical interventions (NPI), vaccination, and infection phases of the coronavirus disease 2019 (COVID-19) pandemic in comparison with levels before the outbreak 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 received 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: before 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 with levels before COVID-19, with 95% confidence intervals (CIs) reported.

Main outcome measures: Incidence rate ratio (IRR) of ON for each period.

Results: A total of 7216 patients (52.7% female patients) were included in the study, with patients receiving a diagnosis of ON as follows: 3770 patients before COVID-19 (2017-2019), 1193 patients during NPI, 1135 patients during vaccination, and 1118 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 with levels before COVID-19 when adjusted for age and sex. The proportions of diagnosis with multiple sclerosis (MS), neuromyelitis optica (NMO), and acute disseminated encephalomyelitis (ADEM) among patients in whom ON developed increased significantly in 2021 in comparison with levels before COVID-19 (10.93% vs. 6.43%; P = 0.0002).

Conclusions: The risks of ON development during the NPI, vaccination, and infection phases of COVID-19 did not increase in comparison with levels before the outbreak in the general population. However, COVID-19 vaccination may be associated with increased risks of ON associated with diseases such as ADEM, MS, and NMO.