Investigation of ametropia in primary school students from first to third grade in Kashgar city

Objective

To investigate the differences in ametropia among school-age children and between Han and Uygur ethnic groups in the main urban area of Kashgar, and to understand the epidemiological characteristics of myopia among children in Kashgar.

Methods

A cross-sectional study was conducted.Random stratified sampling method was used to select the first to third grade students from 6 primary schools in the main urban areas of Kashgar, Xinjiang, from April to June 2018.Visual acuity was examined by the international standard visual acuity chart and refraction was detected by the automatic computer refractometer without cycloplegia.The subjects were classified into low vision (uncorrected visual acuity<0.8 in either eye), hyperopia≥2.00 D, myopia≥-1.00 D, astigmatism≥1.00 D and anisometropia≥1.00 D according to examination results.The percentage of different refraction states and percentage of different ethnic groups among myopic students in the three grades were analyzed.The study protocol was approved by an Ethics Committee of The First People’s Hospital in Kashgar ([2021] QSY No.81).

Results

A total of 6 108 students were enrolled, among which, there were 3 119 males and 2 989 females, 3 395 Uygur and 2 713 Han people, 2 016 first grade, 2 155 second grade and 1 937 third grade students.The detection rate of low vision was 13.5% (825/6 108) in the whole, 21.5% (584/2 713) in the Han people and 7.1% (241/3 395) in the Uygur people, 8.8% (176/2 016) in the first grade, 11.8% (254/2 155) in the second grade and 20.4% (395/1 937) in the third grade.The detection rate of myopia was 9.9% (606/6 108) in the whole, 17.6% (477/2 713) in the Han people and 3.8% (129/3 395) in the Uygur people, 4.4% (89/2 016) in the first grade, 8.1% (174/2 155) in the second grade and 17.7% (343/1 937) in the third grade.There were significant differences in percentage of low vision, myopia, astigmatism and anisometropia among different grades and between the two nationalities (all at P<0.001), and no significant difference in the percentage of hyperopia was found (P>0.05).

Conclusions

The percentage of visual abnormalities and myopia in the first to third grade children in Kashgar is lower than the national average, but the percentage is gradually increasing with age.The percentage of visual abnormalities and myopia among Han pupils is close to the national average, and far higher than that of Uygur pupils.

Refractive errors; Vision screening; Child; Myopia; Vision, low; Astigmatism; Anisometropia; Uygur nationality