Influence of dynamic changes of ocular biometric parameters on new-onset myopia in Chinese children: a 4-year cohort study

To analyze the incidence and progression rates of myopia among children aged 6-8 years in Chengdu, and to evaluate the influence of baseline parameters and dynamic changes in ocular biometric parameters on new-onset myopia risk. A total of 26,169 students aged 6-8 years from eight administrative districts in Chengdu were followed annually for 4 years. All students underwent uncorrected distance visual acuity testing, non-cycloplegic autorefraction, and ocular biometric parameters. Potential risk factors for myopia onset were screened through multivariate logistic regression analysis. The influence of each factor was evaluated using the area under the curve (AUC). Results showed that the baseline prevalence of myopia was 17.8%. The cumulative incidence rates of myopia were 8.1-13.4% (2nd year), 8.6-12.2% (3rd year), and 11.5-16.2% (4th year) across different age groups, with higher rates in older children and females. The mean myopia progression rate was - 0.45 ± 0.32 D/year in the persistent myopia (PM) group. The annual growth rates of axial length(AL) and axial length/corneal radius (AL/CR) ratio in both the new-onset myopia (NOM) group and PM group were higher than those in the persistent non-myopia (PNM) group. The NOM showed significantly higher annual reduction rates in lens thickness and lens power(LP), and higher annual increase rate in anterior chamber depth compared to both PNM and PM. Both baseline parameters (e.g., AL, LP) and their changes 1-3 years before myopia onset significantly influenced the risk of myopia onset (all P < 0.001). The model combining baseline values and annual changes demonstrated good performance with cross-validated AUC values of 0.853. The study demonstrates that baseline values and changes 1-3 years before myopia onset in ocular biometric parameters have important influence on myopia onset, suggesting their incorporation into comprehensive myopia prevention and control systems for children.