Changes in choriocapillaris blood flow density and associated factors affecting axial elongation in Chinese children and adolescents with mild to moderate myopia: a cross-sectional study.

To investigate changes in choriocapillaris blood flow density (CFD) and identify factors influencing axial elongation in Chinese children and adolescents with mild to moderate myopia. A hospital-based cross-sectional study was conducted. A total of 288 participants aged 8 to 15 years were recruited from Tianjin Eye Hospital, including 186 children and adolescents with myopia and 102 age-matched participants without refractive error who served as the control group. Based on cycloplegic spherical equivalent (SE), the myopic participants were further categorized into moderate and mild myopia groups. Refractive power was determined through refraction tests, while various parameters-including axial length (AL) and choriocapillaris flow density (CFD)-were obtained through ophthalmic examinations. Statistical analyses were performed to examine changes in CFD and to identify factors associated with axial length. AL and SE differed significantly among all three groups (all P < 0.001). SFCT was significantly lower in the moderate myopia group compared to the mild myopia and control groups (P < 0.05 for both comparisons), while no significant differences in SFCT or FRT were found between the mild myopia and control groups(all P > 0.05).CFD-peri was significantly lower in the moderate myopia group compared to both the mild myopia and control groups (P = 0.006 and P < 0.001, respectively), while no significant differences were found in CFD-fovea or CFD-para among the three groups(P > 0.05).Spearman correlation analysis revealed significant negative correlations between AL and SE (r = -0.770), SFCT (r = -0.170), CFD-fovea (r = -0.347), CFD-para (r = -0.368), and CFD-peri (r = -0.359) (all P < 0.01). Hierarchical regression analysis identified SE (β = -0.751, P < 0.001) and CFD-peri (β = -0.118, P = 0.005) as independent predictors of axial length, with the final model explaining 71.5% of its variance (R² = 0.715). Choriocapillaris blood flow density in the macular region changes in the early stages of myopia, showing decreases in the perifoveal region. Both SE and CFD-peri may serve as potential biomarkers for predicting axial length elongation in the early stage of myopia.