Trunk-rotation and posture-screening markers in relation to refractive anisometropia among schoolchildren in Nantong, China: a cross-sectional school health surveillance study

School health programmes often collect vision, growth and posture-screening data in the same children, but these streams are usually analysed separately. We examined whether trunk-rotation and posture-screening markers were associated with refractive anisometropia burden in school surveillance. This cross-sectional analysis used 2025 school health surveillance records from Nantong, China. The primary outcome was non-cycloplegic screening-defined refractive anisometropia, defined as an interocular spherical-equivalent difference of 1.00 dioptre (D) or greater. Primary posture-screening markers were maximum angle of trunk rotation (ATR), ATR thresholds and operationally defined inspection or movement-screening indicators. Adjusted prevalence ratios (aPRs) were estimated with modified Poisson regression adjusted for age, sex, body mass index and sampled school-class cluster fixed effects. Among 2605 students, 713 (27.4%) had anisometropia of 1.00 D or greater. The main continuous marker, maximum ATR per 1 degree, was modestly associated with anisometropia (aPR 1.04, 95% CI 1.01 to 1.07). ATR of 7 degrees or greater showed a higher crude prevalence (40.0% versus 26.9%) and a directionally similar but less precise adjusted estimate (aPR 1.30, 95% CI 1.01 to 1.67). Broad myopia and axial-myopia markers showed little corresponding positive pattern. Secondary severity, school-stage and segment-direction analyses were descriptive and exploratory. Trunk-rotation and posture-screening markers were modestly associated with concurrent refractive anisometropia burden in school surveillance data. These findings support integrated analysis of school posture and vision screening data, but should not be interpreted as evidence of temporal order, causality, individual-level prediction, or posture-based ophthalmic referral.