The prevalence of myopia and the factors associated with it among university students in Nanjing: A cross-sectional study

Myopia, a common eye disease, is a global health burden that is increasing worldwide. Although the risk factors for myopia among children have been extensively investigated, those among university students have not. The aim of our study was to investigate the prevalence of myopia and the factors associated with it among university students in Nanjing.Subjects were selected from among the university students using a stratified random sampling method. A total of 1200 first-year university students were invited to participate in the study. A self-reported questionnaire was used to collect data on the students' demographic information, history of parental myopia, and behavioral factors, such as having bad postures while reading or writing, performing eye exercises, taking breaks after 30 minutes of continuous reading, using computers or smartphones, sleep, near-work, and outdoor activity. Univariate analyses were performed to find the associations between myopia and the various parameters. Factors that were statistically significant in univariate analyses were selected as candidate variates for multivariate analysis.The overall prevalence of myopia was 86.8%: 86.1% among males, and 88.0% among females ((2) = 0.68, P=.411). Chi-squared tests showed that parental myopia, performing eye exercises, taking breaks after 30 minutes of continuous reading, and engaging in outdoor activity were significantly associated with myopia (P<.001, P=.034, P<.001, and P=.002, respectively). Having at least 1 parent with myopia was a risk factor for myopia (OR=3.58, 95% CI=1.96-6.54); whereas, taking breaks after 30 minutes of continuous reading and performing at least 2 hours of outdoor activity per day were protective against myopia in multivariate analysis (OR=0.61, 95% CI=0.41-0.93; and OR=0.45, 95% CI=0.2-0.99; respectively).The prevalence of myopia among university students was 86.8%. Parental myopia was a risk factor for myopia. Taking breaks after 30 minutes of continuous reading, and engaging in at least 2 hours of outdoor activity were associated with less myopia. In addition, performing eye exercises was associated with less myopia on univariate analysis.