Thoracic angle of trunk rotation and its association with myopia among schoolchildren in a rural county of northeastern China.

OBJECTIVE: Myopia and poor spinal health are prevalent among schoolchildren. We hypothesized that subclinical postural asymmetry, measured by the thoracic angle of trunk rotation (ATR), is positively associated with myopia in schoolchildren from a rural county in northeastern China. METHODS: This cross-sectional study evaluated 2,599 schoolchildren (grades 1-6) recruited from two primary schools in a single rural county of northeastern China. We measured thoracic ATR using a scoliometer and assessed refractive error. The association between ATR and myopia was analyzed using multivariable logistic regression, restricted cubic spline-based exposure-response modeling, and machine learning for feature importance. RESULTS: Among participants (51.0% boys, 49.0% girls; mean age 9.5 ± 1.7 years), the overall myopia prevalence was 52.8%. After adjusting for confounders, 1° increase in thoracic ATR was associated with 7% higher odds of myopia (odds ratio = 1.07). Children in the highest ATR tertile had significantly increased odds of myopia compared to the lowest. A linear association was identified. Furthermore, feature importance analysis ranked thoracic ATR as a leading marker for myopic status, secondary only to age and gender. CONCLUSION: Elevated subclinical thoracic ATR is independently associated with myopia. As a concurrent epidemiological marker of poor posture, ATR screening supports integrated vision-spine health initiatives for children in resource-limited settings.