目的：调查西部某省两所空军青少年航空学校学生远视力异常分布差异，分析相关影响因素。

方法：本研究为横断面研究，于2017-11/12整群抽取西部地区某省A、B两所青少年航空学校高二、高三年级学生233例，均为男性，年龄15～19岁。采用8方向开口Landolt环形视标视力表检测学生远视力，并通过问卷形式调查影响视力变化的可能因素。分析两所学校学生视力分布情况及视力的相关影响因素。

结果：B校高二、高三年级远视力低于0.8学生比例(18.6%、45.9%)显著高于A校(2.6%、20.0%)，B校高二、高三年级学生远视力整体低于A校，差异均有统计学意义(P<0.05)。B校高二和高三年级学生平均上学日读写时间分别为360(180，535)、470(440，500)min，显著高于A校的200(180，315)、440(400，480)min，差异均有统计学意义(P<0.05)。B校高二、高三年级学生每周户外活动时间分别为420(325，516)、378(265，515)min，明显少于A校的510(439，681)、440(370，601)min，差异均有统计学意义(P<0.05)。B校学生母亲学历初中以上比例显著低于A校(P=0.032)。多因素Logistic回归分析显示，每日读写时间是视力下降的危险性因素(OR=1.109，P=0.010)，每周户外运动时间是视力的保护因素(OR=0.986，P=0.001)； 母亲学历、父亲学历、父母至少一方近视、小学入学年龄、每日上课时间及每周电子产品使用时间不是影响视力的主要因素。

结论：较多的读写时间及较少的户外活动时间是导致视力下降的主要因素，学校近视防控重点在于协调分配读写时间和户外活动时间。

METHODS: The study was a cross-sectional survey. A total of 233 participants were randomly selected from two teenager aviation schools in Western China in November and December of 2017, which were all qualified through the standard of physical examination by Air Force. Distance visual acuity of students was checked and questionnaires about influencing factors of vision were filled voluntarily. Mann-Whitney U rank-sum test and chi-square test were applied for single factor analysis, and Multiple factor Logistic regression analysis was used for the main influence factors of the vision difference.

RESULTS: The proportion of students with less than 0.8 eyesight in school B of Grade 2 and Grade 3 were 18.6% and 45.9%, which was significantly higher than that of 2.6% and 20% of school A. The well-vision distribution in school B of Grade 2 and Grade 3 were lower than that of school A(P<0.05). Single factor analysis showed that school reading and writing time in school B of Grade 2(360min, average: 180-535min)and Grade 3(470min, average: 440-500min)were higher than that of school A(Greade 2: 200min, average: 180-315min; Grade 3: 440min, average: 400-480min; P<0.05); and outdoor activity time of the two grades(Grade 2: 420min, average: 325-516min and Grade 3: 378min, average: 265-515min)were lower than that of school A(Grade 2: 510min, average: 439-681min and Grade 3: 440min, average: 370-601min; P<0.05), and the proportion of students whose mother had a senior high school degree or above in school B was lower than that of school A(P=0.032). Multiple factor Logistic regression analysis showed that reading and writing time was a risk factor for vision loss(OR=1.109, P=0.010)and outdoor activity time was a protective factor(OR=0.986, P=0.001). Mothers' education background, father's educational background, parents' myopia, primary school enrollment age, class time and electronic product using time were not the main factors affecting the vision.

CONCLUSION: More reading and writing time and less outdoor activity time are the main factors for loss of vision, the key point of school myopia prevention needs to coordinate the time between reading, writing and outdoor activity.