Operationalizing a minimal-metric school screening pathway: using non-cycloplegic spherical equivalent as a first-stage triage metric for hyperopia-reserve insufficiency in Chinese schoolchildren.

BACKGROUND

School-based myopia screening commonly relies on non-cycloplegic refraction because cycloplegic refraction is difficult to implement universally at scale. This study evaluated whether non-cycloplegic spherical equivalent (NC-SE) could serve as a low-burden first-stage triage metric to identify children who warrant cycloplegic assessment for possible hyperopia reserve insufficiency (HRI).

METHODS

This cross-sectional school-based study included 1,650 children aged 6-15 years from Zengcheng District, Guangzhou, China. All participants underwent non-cycloplegic autorefraction, UCVA assessment, and cycloplegic autorefraction. Cycloplegic spherical equivalent (Cyclo-SE) was used as the reference standard for defining HRI, cycloplegic myopia, and pseudomyopia. HRI was operationally defined as preserved UCVA with low cycloplegic hyperopic reserve: Cyclo-SE from 0 to + 1.25 D in children aged 6-8 years and from 0 to + 1.00 D in children aged 9-15 years. Diagnostic performance of NC-SE for identifying HRI was assessed using receiver operating characteristic (ROC) analysis.

RESULTS

The prevalence of HRI was 14.1%, 10.5%, and 3.9% in the 6-8, 9-11, and 12-15-year-old groups, respectively. Correlation between NC-SE and Cyclo-SE strengthened with age (Spearman's rho: 0.641, 0.675, and 0.813; all p < 0.001). For detecting HRI, NC-SE achieved an AUC of 0.661 (95% CI: 0.618-0.704). A pragmatic cutoff of -0.50 D yielded a sensitivity of 0.824 (95% CI: 0.765-0.870), specificity of 0.550 (95% CI: 0.524-0.575), PPV of 20.5% (95% CI: 17.9-23.4), and NPV of 95.7% (95% CI: 94.1-96.9). Among children with normal visual acuity, 24.1% had pseudomyopia.

CONCLUSION

NC-SE may serve as a low-burden first-stage triage metric in school-based screening to identify children who warrant cycloplegic assessment for possible HRI. However, its moderate AUC and low PPV indicate that NC-SE should not be interpreted as a stand-alone diagnostic test. Cycloplegic refraction remains necessary for confirming hyperopic reserve status. Further longitudinal studies incorporating axial length, accommodative measurements, and external validation are needed to determine its prognostic value for incident myopia.

CLINICAL TRIAL NUMBER: Not applicable.