Combining visual acuity with refraction reduces overestimation of myopia prevalence in school screenings: an age-stratified analysis

TL;DR

Adding visual acuity to refraction tests in school myopia screenings reduces overestimation, especially in younger children.

Contribution

The study introduces an age-stratified SER + UCVA criterion that improves accuracy in identifying visually significant myopia.

Findings

The SER + UCVA criterion reduced myopia prevalence estimates by 15–21% compared to SER-only.

Overestimation was most severe in children aged 5–6 years, with prevalence nearly double.

From age 10 onwards, myopia prevalence was significantly higher in females than males.

Abstract

School myopia screening commonly employs non-cycloplegic spherical equivalent refraction (SER ≤ −0. 50 D) for its practicality. However, this SER-only approach likely overestimates the prevalence of visually significant myopia, as it cannot distinguish true myopia from accommodative pseudomyopia, especially in younger children. We quantified the disparity between this SER-only criterion and a combined criterion integrating uncorrected visual acuity (UCVA), the SER + UCVA criterion, and examined its variation across age groups.

This serial cross-sectional study (2018–2021) included 20,750 students aged 5–18 years from Southern China. Myopia was defined using two criteria based on non-cycloplegic measurements in at least one eye: (1) SER-only: SER ≤ −0.50 D; and (2) SER + UCVA: SER ≤ −0.50 D plus age-impaired UCVA (>0.20 logMAR at age 5; >0.00 logMAR at ages ≥6) in the same eye. Age-stratified prevalence estimates were compared.

The SER + UCVA criterion yielded consistently lower prevalence estimates than the SER-only criterion (e.g., 48.89% vs. 59.48% in 2021), corresponding to a 15–21% annual relative overestimation. Crucially, this overestimation demonstrated a strong age gradient. It was most severe in young children, with the SER-only myopia prevalence nearly double the SER + UCVA myopia prevalence at ages 5–6 years (relative difference >50%), and progressively narrowed to approximately 10–15% in adolescents (14–18 years). Notably, a significant acceleration in SER + UCVA myopia prevalence was observed in children aged 7–10 years between 2019 and 2020. Furthermore, from age 10 onwards, SER + UCVA myopia prevalence was significantly higher in females than males (all P < 0.001).

Sole reliance on non-cycloplegic SER substantially overestimates the burden of visually significant myopia, especially in younger children. Incorporating UCVA provides a more accurate and functionally relevant metric for public health screening. We advocate for adopting age-specific SER + UCVA criteria in school-based screenings to optimize referral efficiency, with the greatest benefit expected for younger populations where specificity gains are maximal.

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