Table 1 Characteristics of school students (N = 3436).

Age (years), n (%)

 5

35 (1.8%)

23 (1.5%)

58 (1.7%)

 6

429 (22.1%)

227 (15.2%)

656 (19.1%)

 7

317 (16.4%)

269 (18.0%)

586 (17.1%)

 8

210 (10.8%)

218 (14.6%)

428 (12.5%)

 9

148 (7.6%)

151 (10.1%)

299 (8.7%)

 10

132 (6.8%)

70 (4.7%)

202 (5.9%)

 11

148 (7.6%)

91 (6.1%)

239 (7.0%)

 12

109 (5.6%)

82 (5.5%)

191 (5.6%)

 13

82 (4.2%)

83 (5.5%)

165 (4.8%)

 14

69 (3.6%)

57 (3.8%)

126 (3.7%)

 15

65 (3.4%)

56 (3.7%)

121 (3.5%)

 16

72 (3.7%)

59 (3.9%)

131 (3.8%)

 17

61 (3.2%)

58 (3.9%)

119 (3.5%)

 18

61 (3.2%)

54 (3.6%)

115 (3.4%)

 Mean (SD)

9.6 (3.6)

9.9 (3.6)

9.7 (3.6)

Gender: female (%)

999 (51.2%)

741 (49.5%)

1740 (50.6%)

Grade, n (%)

 Kindergarten

414 (21.4%)

199 (13.3%)

613 (17.8%)

 Elementary schooler

1105 (57.0%)

920 (61.4%)

2025 (58.9%)

 Middle schooler

223 (11.5%)

201 (13.4%)

424 (12.3%)

 High schooler

196 (10.1%)

178 (11.9%)

374 (10.9%)

Cycloplegic SER in most myopic eye (diopters): mean (SD)

− 0.07 (2.10)

− 0.37 (2.26)

− 0.20 (2.18)

Myopia in either eye: yes (%)*

652 (33.6%)

617 (41.2%)

1269 (36.9%)

High myopia in either eye: Yes (%)**

40 (2.1%)

51 (3.4%)

91 (2.7%)

Uncorrected visual acuity in worse eye: n (%)

 20/200 or worse

62 (3.2%)

98 (6.5%)

160 (4.7%)

 > 20/200–20/100

117 (6.0%)

108 (7.2%)

225 (6.6%)

 > 20/100 – 20/50

162 (8.4%)

168 (11.2%)

330 (9.6%)

 20/40

56 (2.9%)

68 (4.5%)

124 (3.6%)

 20/33

94 (4.9%)

116 (7.7%)

210 (6.1%)

 20/25

151 (7.8%)

280 (18.7%)

431 (12.5%)

 20/20 or better

1296 (66.9%)

660 (44.1%)

1956 (56.9%)

Biometric measures: mean (SD)

 Axial length (mm)

23.6 (1.3)

23.7 (1.3)

23.6 (1.3)

 Corneal curvature radius (mm)

7.83 (0.25)

7.84 (0.26)

7.84 (0.26)

 Axial length/corneal curvature radius ratio

3.01 (0.15)

3.03 (0.16)

3.02 (0.15)

 Anterior chamber depth (mm)

3.62 (0.3)

3.57 (0.3)

3.60 (0.3)