[An investigative study on the correlation between refractive status and ocular biometric parameters in 3-6-year-old children in Shunyi District, Beijing, China]

Objective: To investigate the relationship between refractive status and ocular biometric parameters in preschool children in Shunyi District, Beijing. Methods: This cross-sectional study employed a random cluster sampling method to measure the ocular axial length (AL), corneal curvature(CR), anterior chamber depth, and horizontal corneal diameter (WTW) using an optical biometer in 3-6-year-old children from 11 kindergartens in Shunyi District, Beijing. The ratio of AL to corneal curvature radius (AL/CR) was calculated. Cycloplegic refraction was performed using 1% cyclopentolate, and the equivalent spherical diopter (SE) was calculated. Ocular biometric parameters were compared among different age groups and refractive statuses. Correlation and regression analyses were conducted between SE and ocular biometric parameters. Results: A total of 1, 142 children completed the examination, with a mean age of (4.52±0.87) years, including 119 three-year-olds, 487 four-year-olds, 362 five-year-olds, and 174 six-year-olds. Among them, 554 were boys and 588 were girls. The mean SE of the examined children was (1.19±0.81) D, AL was (22.27±0.67) mm, corneal curvature radius was (7.73±0.25) mm, and the anterior chamber depth was (3.33±0.67) mm. The mean SE for three-, four-, five-, and six-year-old children was 1.18, 1.19, 1.21, and 1.13 D, respectively. SE showed correlations with AL, AL/CR, and anterior chamber depth (r=-0.350, -0.542, -0.083; all P<0.05), but no correlation with WTW or corneal curvature radius (P>0.05). Among children with different refractive statuses, SE showed stronger correlations with AL and AL/CR in myopic, hyperopic, and highly hyperopic children compared to emmetropic children, and the correlation tended to be stronger with increasing age. The linear regression equations for SE and AL, AL/CR were SE=10.64-0.42·AL and SE=21.48-7.043·AL/CR, respectively. Conclusions: The refractive status of 3-6-year-old children in Shunyi District, Beijing, showed minimal changes. Myopic children had longer AL, deeper anterior chamber, and slightly steeper cornea.