Prevalence and associated factors of myopia and axial length-related visual impairment in children and adolescents aged 4–18 years

The prevalence of visual impairment (VI) increases with axial length (AL) and spherical equivalent (SE). This study aims to explore the prevalence and associated factors of myopia and AL-related VI in children and adolescents, including analysis of sex-specific differences. This cross-sectional survey included 2595 children and adolescents aged 4-18 years from nine educational institutions in a large municipality. The survey comprised a questionnaire, visual acuity examination, refractive screening and AL measurement. The prevalence of myopia and AL-related VI were 56.53% and 50.98% respectively and increased with age (P < 0.01). The myopia rate was higher in females than in males (60.23% vs. 52.71%, χ² = 14.93, P < 0.05), with a significant difference observed in those aged 9 years and older. However, there was no sex difference between in the prevalence of AL-related VI (51.37% vs. 50.61%, χ² = 0.15, P = 0.70). The research showed that older adolescent was a risk factor for both myopia (OR = 2.28, 95%CI = 2.06-2.53) and AL-related VI (OR = 2.49, 95%CI = 2.23-2.77). Having a myopic parent was also significantly associated with myopia (OR = 1.21, 95%CI = 1.12-1.32) and AL-related VI (OR = 1.25, 95%CI = 1.16-1.36). The prevalence of myopia and AL-related VI were high and increased with age in children and adolescents, with sex-specific differences in myopia but not in AL-related VI. Therefore, it is possible to predict the risk of myopia by considering age- and sex-specific factors.