Purpose: To investigate the association between reduced hyperopia and the increased risk of myopia onset in preschool children aged 3-6 years.
Methods: This study utilized data from the Beijing Hyperopia Reserve Research (BHRR) prospective cohort, including 941 children aged 3-6 years who completed baseline and 3-year follow-up assessments (2021-2024). Cross-sectional analyses compared ocular biometry among children with different baseline refractive statuses, followed by longitudinal analyses evaluating the relationship between reduced hyperopia and myopia onset. Children were categorized into pre-myopia and hyperopia groups based on spherical equivalent refraction (SER). The predictive ability of SER for myopia onset was evaluated using receiver operating characteristic analysis, with optimal cutoffs determined by the Youden index. Age-stratified (3-6 years) analyses identified age-specific SER thresholds.
Results: The baseline cross-sectional analysis revealed that there were no significant differences in anterior chamber depth (ACD) or corneal radius (CR) in the pre-myopia group compared to the hyperopia group despite having a significantly lower SER (p < 0.001) and longer AL (p < 0.001). Over 3 years, both groups showed decreasing SER, increasing AL, and deepening anterior chambers (all p < 0.05). Furthermore, in the 5- and 6-year-old groups, the pre-myopia group demonstrated significantly higher rates of change in SER and AL compared to the hyperopia group (all p < 0.05). The optimal SER cut-off value for predicting myopia onset in preschool children was +0.90 D. This cut-off value showed a decreasing trend with age, corresponding to +1.04 D, +0.95 D, +0.87 D, and +0.82 D for children aged 3, 4, 5, and 6 years, respectively.
Conclusions: Preschool children with lower levels of hyperopia, especially those aged 5 and 6, show a significantly higher rate of myopic drift, and AL growth compared to those with greater hyperopia. Enhanced early monitoring and interventions are essential to prevent excessive loss of hyperopia that may accelerate myopia development.
Trial registration: The registration database and the registration number: Chinese Clinical Trial Registry: ChiCTR2000031142.
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