Background: Myopia is a refractive error of the eye that are commonly in school children and it has many risk factors. More than half of the students in some high school in Bac Giang city got myopia. Objective: To identify theo risk factors are related to myopia in students at some high school in Bac Giang city, Bac Giang province. Subjects and Methods: A cross-sectional descriptive study was conducted in Ngo Sy Lien high school and Bac Giang high school for the gifted in 2010. Results: The prevalence of myopia in students have learning time or = 7 hours per day (57.4 percent) was higher than students have learning time 7 hours per day (44.9 percent)
the prevalence of myopia in students have low bowed head reading 30 cm was 82.8 percent, higher than students have not low bowed head reading (18.9 percent)
the prevalence of myopia in students playing computer game time more than 2 hours per day (56.7 percent) was higher than students playing computer game time less than 2 hours per day (45.6 percent)
the differences were statistically significant with p0.05. Playing sport and doing household chores time over 2 hours perday are protective factors to reduce the risk of myopia. The study can not demonstrate other risk factors, including: extra study, watching television and reading stories/books over 2 hours perday, coefficient of classroom lightning or = 0.2, lye reading habit, home learning place, lightning at home with energy saving light bulbs are associated to myopia. Conclusions: Learningi time, learning posture, playing computer game time, doing household chores time and playing sport are related to myopia.