Table 1. Participant characteristics.
| Variable | n = 4,129 (Information from the valid questionnaire and valid information on AL and AL/CR at both baseline and follow-up) | n = 1,934 (Information from the valid questionnaire and valid information on SE at both baseline and follow-up) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Total | Grade 1 | Grade 2 | Grade 3 | Grade 4 | Total | Grade 1 | Grade 2 | Grade 3 | Grade 4 | |
| n | 4,129 | 1,095 | 1,117 | 1,063 | 854 | 1,934 | 543 | 535 | 468 | 388 |
| Age (years) | 8.11±1.17 | 6.67±0.33 | 7.70±0.37 | 8.73±0.42 | 9.71±0.45 | 8.08±1.20 | 6.67±0.33 | 7.70±0.39 | 8.73±0.44 | 9.79±0.47 |
| Gender | ||||||||||
| Boys | 2,220 (53.8) | 588 (53.7) | 584 (52.3) | 583 (54.8) | 465 (54.4) | 1,067 (55.2) | 311 (57.3) | 279 (52.1) | 267 (57.1) | 210 (54.1) |
| Girls | 1,909 (46.2) | 507 (46.3) | 533 (47.7) | 480 (45.2) | 389 (45.6) | 867 (44.8) | 232 (42.7) | 256 (47.9) | 201 (42.9) | 178 (45.9) |
| Height (cm) | 129.51±12.60 | 122.13±6.48 | 127.16±7.80 | 131.82±17.73 | 139.16±8.17 | 129.50±11.41 | 121.82±7.59 | 127.08±7.88 | 132.48±13.65 | 139.98±6.88 |
| Outdoor time (hours/day) | 1.29±1.00 | 1.32±0.92 | 1.27±0.94 | 1.26±1.07 | 1.22±1.02 | 1.35±1.05 | 1.41±1.01 | 1.33±0.97 | 1.33±1.05 | 1.32±1.22 |
| Near work time (hours/day) | 2.95±1.72 | 2.39±1.59 | 2.89±1.54 | 3.38±1.88 | 3.11±1.53 | 3.00±1.74 | 2.54±1.67 | 3.03±1.71 | 3.38±1.89 | 3.12±1.53 |
| Parental myopia | ||||||||||
| Neither | 1,772 (47.5) | 461 (45.6) | 510 (51.3) | 434 (45.4) | 367 (47.8) | 935 (54.3) | 270 (55.0) | 267 (56.1) | 219 (52.9) | 179 (52.5) |
| Either | 1,305 (35.0) | 354 (35.0) | 317 (31.9) | 356 (37.2) | 278 (36.2) | 548 (31.8) | 149 (30.3) | 152 (31.9) | 132 (31.9) | 115 (33.7) |
| Both | 652 (17.5) | 197 (19.5) | 167 (16.8) | 166 (17.4) | 122 (15.9) | 239 (13.9) | 72 (14.7) | 57 (12.0) | 63 (15.2) | 47 (13.8) |