To analyze the differences of the axial length of Mongolian and Han adolescents in different ages and different gender, and provide the basis for the prevention and treatment of myopia in Mongolian and Chinese two groups.

From March 2015 to June 2016, Ordos Mongolia by Erdos Ophthalmologic Hospital of Han nationality in the urban areas of non minority primary school, middle school and high school physical examination data. All of them underwent visual acuity, slit lamp biomicroscopy and ophthalmoscopy, screening out of the body and eyes no abnormalities of Mongolian and Han nationality students in two of 1321 cases (2642 eyes). Among them, there are 309 Mongolian students (618 eyes) and Han Chinese students (2024 eyes), aged from 6 to 18 years old. To measure the axial length of the eyes of the students who were screened. The Mongolian two group of adolescent students according to the different grades are divided into a primary school to the grade one to three, grade four to six, the junior middle school group, and the high school group. Using chi square test to compare the Mongolian two vision abnormal rate; the axial length of the eyes was normal distribution by One-Sample Kolmogrov-Smirnov test and expressed as mean±standard deviation; different grades and different gender groups of axial length were compared using independent samples t-test; the relationship between axial length changes with age growth using a linear regression analysis.

Mongolian two teenagers vision abnormal rate showed that the Mongolian Students′ vision abnormal rate was 29.9%, the Han students′ vision abnormal rate was 41.2%, the difference was statistically significant (χ²=18.27, P<0.05). The axial length of the primary school students from grade one to three was higher than that of the Han students, and the difference was not statistically significant (t=1.36, P>0.05). The length of the axial length was between (22.16±22.08)mm respectively. grade four to six, the junior middle school group, and the high school group of Mongolian students axial length were (23.08±0.08)mm, (23.35±0.10)mm and (23.75±0.03)mm; grade four to six, he junior middle school group, and the high school group of the Han were (23.28±0.04)mm, (23.70±0.03)mm and (24.14±0.01)mm. The axis of Mongolian students is shorter than that of Han Students, the difference was statistically significant (t=2.51, 2.51, 2.63; P<0.05). Comparison of male and female students showed emmetropia axial length, axial length to grade one to three of male and female students were (22.24±0.05)mm and (22.07±0.02)mm, girls axial longer than boys, the difference was statistically significant (t=2.47, P<0.05). The axial length of the eyes to grade four to six of male and female students were (23.08±0.06)mm and (23.28±0.05)mm, the difference was not statistically significant (t=1.46, P>0.05). The axial length of girls and boys in the junior middle school group was (23.35±0.11)mm and (23.70±0.02)mm, respectively. The boys′ axial length was longer than that of girls, and the difference was statistically significant (t=2.52, P<0.05). The axial length of high school group girls and boys were (23.74±0.04)mm and (24.18±0.03)mm, respectively. The boys′ axial length was longer than that of girls, and the difference was statistically significant (t=2.58, P<0.05). Linear regression analysis was conducted between the Mongolian and Chinese two teenagers student′s age and axial, results showed that Mongolian adolescents age axial length had significant (r=0.964, P<0.05); the age of the students in adolescent years also has significant influence on the axis of (r=0.962, P<0.05), and the growth of Chinese students the amount of more than mongolian.

With the increase of age, young people entering the third grade (puberty), axial length of Mongolian students is lower than Han students; the axial length of Mongolian and Han group two adolescents with age were increased. There was no difference in the growth rate of male and female eye axis during the development of adolescent eye.