Table 1 Baseline characteristics of participants mean ± SD or n (%).

N

138

141

132

147

Age (year)

9.49 ± 1.83

9.39 ± 1.92

0.45

8.87 ± 1.69

10.76 ± 1.72

 < 0.001

Body mass index (kg/m²)

17.58 ± 3.49

18.16 ± 3.24

0.33

17.33 ± 3.85

18.78 ± 3.37

 < 0.001

Spherical equivalent refractive error (D)

− 2.79 ± 1.43

− 2.76 ± 1.61

0.32

− 2.27 ± 1.32

− 2.98 ± 1.68

 < 0.001

Intraocular pressure (mmHg)

16.6 ± 3.6

17.0 ± 2.9

0.33

16.98 ± 2.78

16.58 ± 2.91

0.22

Pupil diameter (mm)

6.32 ± 0.66

6.15 ± 0.72

0.56

6.12 ± 0.76

6.07 ± 0.67

0.51

Accommodation amplitude (D)

15.20 ± 5.11

15.39 ± 4.32

0.29

14.87 ± 4.56

15.74 ± 5.25

0.22

Corneal astigmatism (D)

− 1.20 ± 0.48

− 1.22 ± 0.51

0.56

− 1.21 ± 0.58

− 1.24 ± 0.57

0.33

Corneal curvature (D)

42.82 ± 1.52

42.85 ± 1.41

0.69

42.81 ± 1.37

42.92 ± 1.45

0.66

Anterior chamber depth (mm)

3.64 ± 0.22

3.67 ± 0.19

0.76

3.60 ± 0.21

3.68 ± 0.27

 < 0.001

Axial length (mm)

24.61 ± 0.72

24.59 ± 0.74

0.21

24.26 ± 0.81

24.68 ± 0.93

 < 0.001

Outdoor activity (hours per day)^a

2.53 ± 1.38

2.60 ± 1.32

0.67

2.52 ± 1.31

2.61 ± 1.35

0.21

Nearwork (hours per day)^#

14.11 ± 2.01

14.23 ± 1.82

0.59

14.02 ± 2.82

14.22 ± 1.52

0.45

Sex

Male

78

67

0.13

73 (55.3%)

72 (49.0%)

0.29

Female

60

74

59 (44.7%)

75 (51.0%)

Heredity

 +  + (both parents myopic)

36

30

32 (24.2%)

34 (23.1%)

0.90

 + – (one parent myopic)

62

73

0.48

62 (47.0%)

73 (49.7%)

−− (neither parent myopic)

40

32

38 (28.8%)

40 (27.2%)