Table 2. Comparison of demographic biological characteristics, SER, and ocular biometric parameters between the control group and the intervention group.
| Parameters | Control group (n=875)a | Intervention group (n=931)a | t/χ2 | P |
| Age (y) | 7.59±0.53 | 7.41±0.54 | 7.017 | 0.001 |
| Male (%) | 460 (52.57) | 507 (54.46) | 0.645 | 0.422 |
| Height (m) | 1.31±0.07 | 1.31±0.07 | 1.453 | 0.146 |
| Body weight (kg) | 28.52±7.21 | 27.94±6.84 | 1.434 | 0.152 |
| Body mass indexb | 16.43±3.55 | 16.29±3.57 | 0.6544 | 0.513 |
| Wearing glasses (%) | 85 (14.3) | 98 (14.5) | 0.014 | 0.906 |
| Uncorrected visual acuity | 0.86±0.24 | 0.88±0.22 | -1.567 | 0.117 |
| Spherical equivalent refraction (D) | -0.34±1.07 | -0.39±1.01 | 1.113 | 0.256 |
| Prevalence of myopia (%) | 73/875 (8.5) | 87/861 (10.1) | 0.1256 | 0.723 |
| Axial length (mm) | 23.08±0.83 | 23.09±0.81 | -0.2568 | 0.797 |
| Corneal curvature (D) | 43.27±1.44 | 43.22±1.44 | 0.691 | 0.488 |
| White to white distance (mm) | 12.19±0.39 | 12.20±0.38 | -0.895 | 0.371 |
| Anterior chamber depth (mm) | 3.38±0.24 | 3.37±0.36 | 0.902 | 0.377 |
| Outdoor time per day (%) | ||||
| <2h | 508 (85.4) | 598 (88.6) | 2.906 | 0.088 |
| >2h | 87 (14.6) | 77 (11.4) | ||
| Parental myopia (%) | ||||
| No | 143 (24.2) | 184 (27.7) | 2.432 | 0.296 |
| Father or mother | 254 (43.1) | 262 (39.4) | ||
| Father and mother | 193 (32.7) | 219 (32.9) |
aRight eye data for students who completed baseline examination. bCalculalted as weight in kilograms divided by height in meters squared. SER: Spherical equivalent refraction.