Behavioral and Structural Correlates of Axial Length in School-Aged Children: Baseline Findings from the Seoul Myopia Cohort Study.

Multivariable linear mixed-effects models identified factors associated with axial length and macular thickness.

Older age, a greater number of myopic parents, flatter corneal curvature, male sex, continuous smart device use exceeding 1 h per session, and viewing distance < 30 cm were independently associated with longer axial length.

Each 1 mm increase in axial length was associated with significant subfoveal choroidal thinning and generalized extrafoveal macular thinning, whereas the central fovea remained relatively preserved.