To determine the distribution of OBC, including axial length (AL), lens thickness (LT) and vitreous chamber depth (VCD), examine their relationship to personal characteristics and examine relationship between spherical equivalent refraction (SE) with AL and VCD adjusted for and personal characteristics included age, sex, height, weight and place of residence.

Among 6 to 12 year-old children, urban subjects were selected using random cluster sampling, and in rural areas, all eligible subjects were considered for enrollment. Ocular biometrics were measured using Biograph for all children. Data was summarized as mean and 95% confidence intervals. Linear regression was used to investigate the relationships between the study variables.

Data from 4938 children were analyzed. Mean AL, LT, and VCD were 23.02 (95% CI: 22.97-23.07) mm, 3.48 (95%CI: 3.47-3.49) mm, and 20.63 (95%CI: 20.59-20.66) mm, respectively. According to the multiple linear regression model, AL correlated positively with height (β=0.020, P<0.001) and inversely with male gender (β=-0.522, P<0.001). LT correlated positively with age (β=-0.019, P<0.001) and inversely with female gender (β=0.043, P<0.001), while VCD had a positive relationship with height (β=0.018, P<0.001) and an inverse relationship with age (β=-0.020, P=0.04) and female gender (β=-0.386, P<0.001). Adjusted for personal characteristic; Spherical equivalent (SE) had an inverse relationship with AL (β=-0.441, P<0.001) and a positive relationship with LT (β=0.423, P<0.001). Among the studied variables, AL had the strongest association with SE (standardized coefficient: -0.39).

The AL value was almost similar to European countries, but less than that in the Eastern and Southeast Asian populations. The OBC value in 6-12 year old children was influenced by age, height, and gender.