方法：采用分层整群抽样方法抽取2 209名初中生作为调查对象，采用自制调查问卷收集性别、年龄、民族、年级、用眼行为、体育锻炼以及父母视力情况等，同时检测角膜曲率、前房深度和眼轴长度。

结果：研究对象近视患病率为48.02%，其中轻度近视、中度近视和高度近视分别占40.74%，35.31%和23.96%。角膜曲率、前房深度和眼轴长度在视力正常与不同程度近视研究对象间存在统计学差异(P<0.05)。不同性别、民族、年级、视近距离、坐姿、眼保健操、每周户外活动时间以及父母视力情况研究对象近视患病率间存在统计学差异(P<0.05)。Logistic回归分析表明性别、民族、年级、视近距离、坐姿、眼保健操、每周户外活动时间以及父母视力情况是影响近视发生的因素。

结论：坐姿不正确、父母近视、视近距离<20cm、眼保健操不正确以及户外活动时间少等引起初中生近视的主要原因，应针对上述因素采取有效的预防控制措施。

METHODS: Totally 2 209 junior school students were extracted as respondent with stratified cluster sampling method. The gender, age, ethnicity, grade, eye behavior, physical activity and parental visual conditions were collected by self-made questionnaire, and the curvature of the cornea, anterior chamber depth and axial length were detected.

RESULTS: The prevalence of myopia was 48.02%, including the mild myopia, moderate myopia and high myopia were 40.74%, 35.31% and 23.96% respectively. Curvature of the cornea, anterior chamber depth and axial length had statistical difference between normal vision and different degrees of myopia(P<0.05). The prevalence of myopia had statistical difference in different gender, ethnicity, grade, visual near distance, sitting posture, eye exercises, outdoor activity time each week and the case of parents eyesight(P<0.05). Gender, ethnicity, grade, visual close range, sitting posture, eye exercises, outdoor activity time each week and the case of parents eyesight were the factors affecting the occurrence of myopia by using logistic regression analysis.

CONCLUSION: Incorrect sitting posture, parental myopia, visual near distance <20cm, incorrect eye exercises and less time for outdoor activities are the main reasons that cause myopia of junior students. The effective prevention and controlled measures should be taken for these factors.