Age-specific distribution of oculometric parameters and myopia in children aged 8-12y

Aim: To describe the distribution of ocular biometrics and to evaluate its associations with refractive error and to assess the contribution from ocular parameters to refractive error among Chinese myopic children.

Methods: This cross-sectional study evaluated subjects aged 8-12y. Keratometry, ocular biometry, and cycloplegic autorefraction were performed on each subject. Spherical equivalent refraction (SER) and ocular biometrics were assessed as a function of age and gender. The Pearson correlation analysis between SER and ocular biometrics was carried out. Multiple linear regression was performed to analyze the association between SER and ocular parameters.

Results: A total of 689 out of 735 participants (321 boys, 48.1%) were analyzed, with a mean SER of -2.98±1.47 diopter (D). Axial length (AL), anterior chamber depth (ACD), corneal radius of curvature (CR), horizontal visible iris diameter (HVID), central corneal thickness (CCT) and lens power (LP) showed normal distribution. The AL, AL/CR ratio, ACD and CR increased from 8 to 12y of age, while SER and LP decreased, HVID and CCT remained stable. There was no difference in gender. SER decreased by 0.929 D for every 1 mm increase in AL and decreased by 1.144 D for every 0.1 increase in AL/CR ratio. The Pearson correlation coefficient between SER and AL was -0.538 (P<0.01) and -0.747 (P<0.01) between SER and AL/CR ratio. For the SER variance, AL explained 29.0%, AL/CR ratio explained 55.7%, while AL, CR, ACD and LP explained 99.3% after adjusting for age and gender.

Conclusion: The AL, CR, ACD and LP are the most important determinants of myopic refractive error during myopia progression.