Anisometropia and its correction in children in northwest China: A study based on autorefraction data.

Background: To investigate the prevalence and correction of anisometropia among primary school children in northwestern China.

Methods: A cross-sectional school-based study was conducted in Shaanxi Province. Visual acuity (VA) and autorefraction without cycloplegia were assessed in all participants, and some received axial length (AL) measurements. Anisometropia was categorised based on spherical equivalent (SE), cylindrical (CYL), and AL. The prevalence of anisometropia and refractive correction across different ages and sexes, and correlations between ocular parameters, were analysed.

Results: The study included 29 153 children aged 6-12 (mean age 9.52 ± 1.73 years) for VA and autorefraction measurements, and 1176 children for AL measurements. The prevalence of myopia (SE ≤ -0.50 D), hyperopia (SE ≥ +0.50 D), and anisometropia (interocular SE difference ≥1.00 D) was 65.26%, 15.09%, and 16.50%, respectively. Anisometropia severity, based on SE (χ² = 443.758, p < 0.001), CYL (χ² = 41.669, p < 0.001), and AL (χ² = 95.505, p < 0.001), increased with age, with no significant differences between sexes. Interocular SE difference correlated with interocular spherical power (r = 0.806, p < 0.001), CYL (r = 0.21, p < 0.001), and AL (r = 0.365, p < 0.001). Additionally, interocular CYL difference was positively correlated with interocular AL difference (r = 0.16, p < 0.001). Despite the high prevalence of anisometropia, less than 30% of affected children received refractive correction.

Conclusions: Anisometropia of SE, CYL, and AL increased progressively with age. Despite the elevated prevalence of anisometropia, the utilisation of refractive correction remained strikingly low.