Researchers have documented a significant increase in both the prevalence and severity of refractive and corneal astigmatism in Hong Kong schoolchildren following the COVID-19 pandemic. In their study, which included 21,655 children aged 6 to 8 years and spanned from 2015 to 2023, they found that the increases occurred independently of myopia and were likely linked to pandemic-induced lifestyle changes.

Data from the Hong Kong Children Eye Study, which recruited participants across all primary schools in Hong Kong, was analyzed and stratified by hospital service clusters. Pediatric participants underwent comprehensive cycloplegic ocular exams, and data were collected using standardized protocols. The cohort included 11,464 boys (52.9%) and 10,191 girls (47.1%) who were a mean age of 7.31 years.

Refractive and Corneal Astigmatism

The researchers found that the prevalence of refractive astigmatism (RA) of at least 1D rose from 23.4% between 2015 and 2019 to 24.6% at the onset of the pandemic in 2020. It continued to increase to 30% in 2021, and rose to 34.7% by 2023. Mean cylinder power also increased from 0.70D to 0.87D during this period. Postpandemic, the odds ratio (OR) for RA was 1.20 (95% confidence interval [CI] = 1.09–1.33; P<.001).

The prevalence of corneal astigmatism (CA; at least 1D) increased from 59.7% between 2015 to 2019 to 66.9% in 2021, and rose to 64.7% by 2023. The OR for CA postpandemic was 1.26 (95% CI = 1.15–1.38; P<.001). Like RA, mean cylinder power for CA increased from 1.24D to 1.35D.

These increases were observed across all age and sex subgroups, and “the pandemic itself imposed additional odds of RA and CA by 20%, or by a magnitude of 0.04D,” the authors wrote, led by Ka Wai Kam, MSc, of the Department of Ophthalmology and Visual Sciences at The Chinese University of Hong Kong.

Regression models showed that the increase in RA and CA persisted after adjusting for age, sex, family income, parental astigmatism, and spherical refractive error. The postpandemic period was associated with a reduction in outdoor time from 1.43 to 1.16 hours per day (P<.001) and an increase in near work from 3.33 to 4.91 hours per day (P<.001). These behavioral changes may have contributed to structural changes in the developing cornea, the authors suggested.

Corneal Curvature and Directionality

The steepest keratometry value (K2) increased slightly from 44.15D to 44.2D postpandemic, while the flattest keratometry (K1) slightly declined. The widening K1–K2 difference suggested an increase in vertical steepening, which was consistent with with-the-rule astigmatism. The authors hypothesized that prolonged downward gaze during digital device use may have impacted superior corneal curvature, especially in the vertical meridian.

Temporal Relationship With Myopia

Although myopia prevalence increased during the pandemic onset in 2019 and 2020, astigmatism prevalence rose with a delay, beginning in 2021 and persisting through 2023. The authors suggested that changes in corneal curvature may require longer exposure and adaptation time compared with axial elongation seen in myopia. They also found that the increase in astigmatism among pediatric patients appears to be independent of parental astigmatism as well.

“Given the high prevalence of 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, in order to preserve children’s eyesight and quality of life,” the authors concluded.

A full list of author disclosures can be found in the published research.

Source: JAMA Ophthalmology