Prevalence and influencing factors of myopia among primary and secondary school students in Urumqi: a cross-sectional study with interrupted time series analysis
Authors: Lu Junwen , Shi Haonan , Yao Jian , Hu Bin , Wang Shaofei , Li Xuemei , Wang Yingxia , Wang Xiaolan , Xie Daming , Wang Xiaowei , Yao Xuemei , He Xiaojing , Zhu Aiyong , Yu Huaijiang , Wang Tingting 
Published: August 2023

Background
Myopia has become a public health problem faced worldwide. This study aimed to evaluate the prevalence trends of myopia and to explore the influencing factors of myopia, then to provide a basis for myopia prevention and control among schoolchildren.
Method
Using a cross-sectional study method, a questionnaire was administered in December 2019 for 9503 students of primary school third- to high school second-year from 11 schools in 4 districts of Urumqi city. The questionnaire included visual situation of students, individual factors, and environmental factors to analyze the influence of individual factors and environmental factors on myopia among schoolchildren. In addition, we also compared the prevalence trends of myopia in 2012 and 2019.
Result
After standardizing the study phases, the myopia rates for primary and secondary students in Urumqi in 2012 and 2019 were 45.9% and 43.7%, respectively. Among them, the myopia rate of students in the primary school stage in 2019 was higher than that in 2012 (χ2 = 17.87, P < 0.05); There was no significant difference in myopia among students in the junior high school stage between 2012 and 2019 (χ2 = 1.38, P > 0.05); High school students in 2012 were more myopic than those in 2019 (χ2 = 25.19, P < 0.05); The myopia rates were higher in female than male students and lower in Han than in other ethnic groups (all P < 0.05). Multivariate logistic regression suggested that in 2012, students' eyes when reading and writing were less than 30cm away from books (OR = 1.51, 95%CI = 1.28–1.78), poor reading and writing habits (OR = 1.55, 95%CI = 1.26–1.91), hours of computer use per day (OR = 1.21, 95%CI = 1.00-1.46), and parental myopia (OR = 2.11, 95%CI = 1.65–2.71) were risk factors for myopia; Eye exercises (OR = 0.66, 95%CI = 0.53–0.81), time spent outdoors per day (OR = 0.84, 95%CI = 0.71-1.00), and time spent sleeping per day (OR = 0.75, 95%CI = 0.60–0.95) were protective factors for myopia. In 2019, students' eyes when reading and writing were less than 30 cm away from books (OR = 1.69, 95%CI = 1.56–1.82), poor reading and writing habits (OR = 1.22, 95%CI = 1.09–1.36), and parental myopia (OR = 2.22, 95%CI = 2.03–2.43) were risk factors for myopia; Eyes were rested after reading and writing for 1 h (OR = 0.79, 95%CI = 0.74–0.84), eye exercises (OR = 0.87, 95%CI = 0.79–0.95), hours of watching television per day (OR = 0.85, 95%CI = 0.79–0.92), frequently looking into distance (OR = 0.85, 95%CI = 0.74–0.98), time spent outdoors per day (OR = 0.90, 95%CI = 0.83–0.98), time spent sleeping per day (OR = 0.84, 95%CI = 0.75–0.94), and numbers of eating zhuafan per week (OR = 0.85, 95%CI = 0.77–0.95) were protective factors for myopia.
Conclusion
At present, the myopia rate of elementary and secondary students in Urumqi is high, and there is a trend towards lower age. The prevention and control of myopia should be initiated actively by correcting the poor reading and writing habits of students, increasing their outdoor activities and sleep time, and reasonably improving the dietary structure of the students.