Visual development cohort study on refractive parameters among preschool children in Sucheng district

To examine the dynamic changes in visual acuity and refractive parameters among preschool children in Sucheng District, Suqian City, addressing the lack of refractive development data for preschool-aged populations in rapidly urbanizing fourth-tier cities in China, and to offer a foundation for regional vision screening and intervention strategies.

A prospective longitudinal cohort study (2022-2024) was conducted. Utilizing stratified cluster sampling, 2,821 children (5,642 eyes) from 51 kindergartens in Sucheng District were selected and underwent three annual follow-ups. Non-cycloplegic refraction (Spot VS100 photorefractor(Welch Allyn, USA) and examinations using a standard logarithmic visual acuity chart were performed. Differences in visual impairment rates, refractive status distribution, spherical equivalent (SE), and other parameters by age and sex were analyzed.

Visual impairment rates at baseline (2022), interim (2023), and final (2024) assessments were 6.45%, 5.17%, and 8.68%, respectively (χ²=28.20, P < 0.001), displaying a nonlinear U-shaped trajectory. At the final assessment, the impairment rate among girls (10.89%) was significantly higher than that of boys (6.52%) (χ²=16.88, P < 0.05). Astigmatism and SE values initially increased and then decreased over the three-year period (P < 0.001). With age, the proportion of pure hyperopia showed a significant decline (P < 0.001), while pure myopia proportions increased correspondingly (P < 0.001).

Refractive development among preschool children in Sucheng District is significantly impacted by rapid urbanization, characterized by an accelerated depletion of hyperopic reserve and an earlier-than-expected emmetropization process. Girls and children aged 5-6 years (final assessment period) represent high-risk groups for visual impairment, underscoring the need for an annual kindergarten-based screening and early intervention system.