Prevalence and Severity of Astigmatism in Children After COVID-19

Importance: Astigmatism can cause blurred vision at near and distance. It is common among schoolchildren and associated with ametropia. Although the COVID-19 pandemic generated a surge in myopia prevalence in children, the association with child astigmatism remains unknown. Objective: To report the prevalence of refractive astigmatism and corneal astigmatism in schoolchildren from 2015 to 2023 and explore the associations between the pandemic and astigmatism. Design, Setting, and Participants: This population-based cross-sectional study stratified all the primary schools registered with Education Bureau in Hong Kong into 7 clustered regions used by Hospital Authority Services in Hong Kong. Participants were schoolchildren aged 6 to 8 years who underwent comprehensive ocular examinations at 2 academic medical centers in Hong Kong from 2015 to 2023. Astigmatism was measured with optical biometry and auto-refractor after cycloplegia. Exposure: COVID-19 pandemic. Main Outcomes and Measures: The annual prevalence rates of refractive astigmatism and corneal astigmatism were the primary outcome measures. Logistic regression was used to evaluate the association of the pandemic with the risks of refractive astigmatism and corneal astigmatism. Linear regression was used to explore the association of the pandemic with the magnitudes of refractive astigmatism and corneal astigmatism. Results: The cohort consisted of 21 655 children: 11 464 boys (52.9%) and 10 191 girls (47.1%); their mean (SD) age was 7.31 (0.90) years. The prevalence rate of refractive astigmatism of at least 1.0 diopter (D) was 21.4% and corneal astigmatism of at least 1.0 D 59.8% in 2015 and increased to 34.7% (difference, 13.3%; 95% CI, 9.3%-17.3%) and 64.7% (difference, 4.9%; 95% CI, 0.5%-9.2%), respectively, in 2022-2023. The pandemic was associated with a 20% increase in the risk of refractive astigmatism (odd ratio [OR], 1.20; 95% CI, 1.09-1.33; P < .001), 26% increase in the risk of corneal astigmatism (OR, 1.26; 95% CI, 1.15-1.38; P < .001), 0.04 D in the magnitude of refractive astigmatism (95% CI, 0.02-0.07; P < .001), and 0.05 D in the magnitude of corneal astigmatism (95% CI, 0.02-0.08; P < .001), compared with the prepandemic period of 2015-2019 and after adjusting for sociodemographic factors, parental astigmatism, and child myopia. Conclusions and Relevance: This study found an increase in both the prevalence and severity of refractive astigmatism and corneal astigmatism after the COVID-19 pandemic. Corneal changes especially along the steepest meridian may explain some of the progression of corneal astigmatism. The potential impact of higher degrees of astigmatism may warrant dedicated efforts to elucidate the relationship between environmental and/or lifestyle factors, as well as the pathophysiology of astigmatism.