Table 1 Baseline Characteristics of primary school children

n

1294

184

1110

/

Age, mean ± SD, year

7.29 ± 0.91

7.59 ± 0.83

7.24 ± 0.91

< 0.001

Sex, n(%)

606 (46.8%)

78 (42.4%)

528 (47.6%)

0.192

BMI, mean ± SD, kg/m²

16.42 ± 2.33

16.75 ± 2.65

16.37 ± 2.27

0.066

SER, mean ± SD, D

−0.25 ± 0.94

−1.97 ± 0.95

0.03 ± 0.56

< 0.001

AL, mean ± SD, mm

23.05 ± 0.84

23.83 ± 0.98

22.92 ± 0.74

< 0.001

CRC, mean ± SD,,mm

7.81 ± 0.25

7.76 ± 0.24

7.82 ± 0.26

0.006

AL/CRC ratio, mean ± SD

2.95 ± 0.09

3.07 ± 0.10

2.93 ± 0.07

< 0.001

Nearwork time, mean ± SD, h/d

3.25 ± 0.92

3.28 ± 0.90

3.24 ± 0.92

0.654

Outdoor time, mean ± SD, h/d

1.88 ± 0.74

1.85 ± 0.71

1.89 ± 0.75

0.462

 0

263 (20.3%)

25 (13.6%)

238 (21.4%)

< 0.001

 1

489 (37.8%)

51 (27.7%)

438 (39.5%)

 2

542 (41.9%)

108 (58.7%)

434 (39.1%)