A 2-year cohort study of ocular bioparameters in non-myopic primary schoolchildren with different refractive states

This study aimed to investigate the determinants of early myopic progression in emmetropic children through a comprehensive analysis of refractive profiles, axial length (AL), and axial length/corneal radius (AL/CR) ratio. A cohort study was conducted on 206 non-myopic primary school students (age: 6-10 years). Participants were stratified into 3 hyperopic reserve groups: adequate, relatively insufficient, and severely depleted. longitudinal monitoring over 24 months included annual cycloplegic refraction measurements, AL, and AL/CR ratio. At the 12-month follow-up, the incidence of myopia was 32.5%. The 3 groups exhibited statistically significant differences in spherical equivalent progression (-0.70 ± 0.46 D vs -0.56 ± 0.45 D vs -0.38 ± 0.36 D; P < .001) and AL elongation (0.40 ± 0.17 mm vs 0.31 ± 0.18 mm vs 0.27 ± 0.16 mm; P < .001). At the 24-month follow-up, the cumulative incidence of myopia was 52.4%. The 3 groups exhibited significant differences in spherical equivalent progression (-1.31 ± 0.67 D vs -1.02 ± 0.68 D vs -0.86 ± 0.65 D; P < .001) and AL elongation (0.74 ± 0.29 mm vs 0.59 ± 0.26 mm vs 0.56 ± 0.31 mm; P < .001). Baseline AL/CR ratios differed significantly across groups (3.00 ± 0.50 vs 2.94 ± 0.49 vs 2.87 ± 0.63; P < .001). Multivariate logistic regression analysis confirmed relative hyperopic insufficiency as an independent risk factor for myopia onset over 24 months. The phase of suboptimal hyperopic reserve serves as a precursor biomarker for pre-myopia, warranting prioritized monitoring for proactive myopia control. To optimize preventive efficacy, targeted interventions should be initiated during the second annual follow-up in longitudinal cohorts.