Influencing factors of degree of myopia among primary and secondary school students in Shaanxi province: a cross-sectional survey with factor analysis

  Objective   To investigate the prevalence and impact factors of various degree of myopia among primary and secondary school students in Shaanxi province for providing evidences to the development of myopia prevention and control strategies.

  Methods   Totally 46 878 students at ages of 6 – 18 years were recruited from 162 primary/secondary/vacation schools in 20 districts/counties of 10 municipalities, Shaanxi province; visual acuity test and questionnaire survey were conducted among the students during 2019. Factor analysis and ordered logistic regression analysis were used to explore influencing factors of degree of myopia.

  Results   Among the 45 102 students completing the survey effectively, 23 523 (52.16%) were identified suffering from myopia. In the myopic students, the ratio of mild myopia decreased with school year but that of moderate and high myopia increased with school year significantly (χ² = 3069.587, P < 0.001). Seven common factors for degree of myopia were extracted with factor analysis and the cumulative variance contribution of the common factors was 49.10%. Ordered multivariate logistic regression analysis demonstrated that school related factor (odds ratio OR = 0.700, 95% confidence interval 95% CI: 0.680 – 0.721) and reading and writing posture factor (OR = 0.922, 95% CI: 0.896 – 0.950) were protective factors for degree of myopia (both P < 0.001); while, eye habit factor (OR = 1.114, 95% CI: 1.083 – 1.146), electronic product use related factor (OR = 1.002, 95% CI: 0.974 – 1.031), eye distance factor (OR = 1.036, 95% CI: 1.007 – 1.067), study and eye rest interval time factor (OR = 1.148, 95% CI: 1.115 – 1.182), family related factor (OR = 1.297, 95% CI: 1.260 – 1.335) were risk factors for degree of myopia (all P < 0.001).

  Conclusion   Among primary and secondary school students in Shaanxi province, myopia is highly prevalent; family-related factor is the most important risk factor for degree of myopia and school-related factor is the most prominent protective factor. The results suggest that interventions should be implemented actively to control the progress of myopia among the students, especially among those with family history of myopia.