Juvenile myopia is a serious problem in China, the prevalence of which stays at a high level and shows an upward trend.
The prevalence of myopia for Chinese school-aged students is one of the highest in the world, and is higher in the city of Beijing (46.87% for primary school students, 71.02% for junior high school students, and 84.79% for senior high school students) than the national average and has shown an upward trend.
Many studies have reported the possible environmental, behavioral and genetic risk factors for myopia, but the strength of these associations is often weak, and some prior results are often contradictory. Commonly investigated risk factors include environmental risk factors such as parental education, family income, and illumination condition, and behavioral risk factors such as reading distance, time outdoors and physical activity, hours spent watching TV or using a computer, and length of time sleeping, as well as parental myopia, a possible indicator of genetic susceptibility. Studies focusing on reducing the progression of myopia have had limited success.
In Yanhong Gong’ research review from School of Social Development and Public Policy at Beijing Normal University, published in Health, 2014 Vol.1 by Scientific Research Publishing. A cross-sectional analysis in a random sample survey was conducted in Beijing in 2008. The data collected from 15,316 Chinese school students aged 6 to 18 years, randomly selected from 19 schools were evaluated, including non-cycloplegic refraction and possible genetic, environmental and behavioral factors, to explore the key risk factors for myopia. Univariate and multiple logistic regression analyses were per-formed to compare the OR values, and receiver operator characteristic (ROC) curves were generated to compare the differences among the areas under the ROC curves using the method of multiple comparison with the best. Results showed that the odds ration of myopia was 3.37 for students whose sleep time was 7 hours compared with students whose sleep time was 9 hours. Analysis of the areas under the ROC curves showed five variables with predictable values better than chance: age, sleeping time, reading or writing distance, hours of studying, and parental myopia.
It was not surprising, as proved by other studies, that parental myopia, reading or writing distances, time spent on studying or other activities by using eyes were dominant risk factors associated with juvenile myopia. Our findings indicated that hours of sleeping were also closely related to juvenile myopia, in which the underlying mechanism should be explored in the future study.