Prevalence of binocular dysfunction, myopia and anisometropia in urban school-aged children in Chengdu, China: a cross-sectional screening study

This study aimed to investigate the prevalence of binocular vision dysfunction, myopia and anisometropia among students at a primary school in Chengdu, China, and to analyze their correlations. A cross-sectional study was conducted in May 2023, involving 1,415 students aged 6–12 years from an urban primary school in Chengdu, China. Refractive status and binocular visual functions (including perceptual eye position and foveal suppression) were examined to explore the associations between myopia, anisometropia, and binocular vision abnormalities. The prevalence of myopia was 41.70%, and the rate of anisometropia (≥ 1 D) was 15.83%. Both conditions increased significantly with age ( p < 0.001), with no gender differences observed ( p = 0.187 and 0.316). Myopic participants had a higher prevalence and greater magnitude of anisometropia than non-myopic individuals (both p < 0.001). Conversely, myopia prevalence was higher in the anisometropic group ( p < 0.001). Binary logistic regression showed that myopia was associated with both the prevalence and degree of anisometropia (OR = 2.896; 95%CI: 2.087–4.018 and OR = 2.529; 95%CI: 1.992–3.210). The prevalence of abnormal perceptual eye position was 58.31% in myopes and 69.70% in non-myopes, with the latter being significantly higher ( p < 0.001). Foveal suppression was significantly more prevalent in myopic individuals (47.29% vs. 29.21%, p < 0.001). Myopic children exhibited more prevalent foveal suppression, which is potentially linked to accommodative dysfunction. This dysfunction, characterized by interocular retinal disparities and cortical imbalance, appears to coexist with compromised eye position control. A significantly higher prevalence of abnormal perceptual eye position was observed in non-myopes than in myopes, suggesting that the relationship between refractive status and perceptual eye position warrants further investigation. The positive correlation between anisometropia and myopia suggests that anisometropia may be a potential associated factor for myopia development.