Table 1.
Characteristics of all participants.
| Variables | Overall | Urban | Rural | P |
|---|---|---|---|---|
| N (subjects, %) | 4,522 | 2,429 (53.72) | 2,093 (46.28) | |
| Gender | 0.062 | |||
| Male (%) | 2,336 (51.66) | 1,286 (52.94) | 1,050 (50.17) | |
| Female (%) | 2,186 (48.34) | 1,143 (47.06) | 1,043 (49.83) | |
| Age (year) | <0.001 | |||
| 6–10 | 1,708 (37.77) | 856 (35.24) | 852 (40.71) | |
| 11–15 | 1,797 (39.74) | 855 (35.20) | 942 (45.00) | |
| 16–18 | 1,017 (22.49) | 714 (29.56) | 299 (14.29) | |
| Height (cm) | 151.28 ± 19.67 | 152.97 ± 19.95 | 149.26 ± 19.12 | <0.001 |
| Weight (cm) | 45.82 ± 18.96 | 46.98 ± 19.48 | 44.44 ± 18.18 | <0.001 |
| BMI (kg/m2) | 19.18 ± 4.60 | 19.19 ± 4.64 | 19.15 ± 4.56 | <0.001 |
| Parental refractive error (%) | <0.001 | |||
| Myopia | 1,580 (34.94) | 918 (37.79) | 662 (31.63) | |
| No Myopia | 2,942 (65.06) | 1,511 (62.21) | 1,431 (68.37) | |
| Parental education level (%) | <0.001 | |||
| Junior high school | 1,649 (36.47) | 574 (23.63) | 1,075 (51.36) | |
| Senior high school | 1,286 (28.44) | 668 (27.50) | 618 (29.53) | |
| Bachelor | 1,365 (30.19) | 986 (40.59) | 379 (18.11) | |
| Master | 222 (4.90) | 201 (8.28) | 21 (1.00) | |
| Annual household income (yuan, %) | <0.001 | |||
| >200,000 | 504 (11.15) | 373 (15.36) | 131 (6.26) | |
| ≤ 200,000 | 4,018 (88.85) | 2,056 (84.64) | 1,962 (93.74) | |
| Daily hours of near-work (%) | 0.981 | |||
| <2 h | 331 (7.32) | 178 (7.33) | 153 (7.31) | |
| ≥2 h | 4,191 (92.68) | 2,251 (92.67) | 1,940 (92.69) | |
| Daily hours of outdoor activities (%) | <0.001 | |||
| >2 h | 2,790 (61.70) | 1,348 (55.50) | 1,442 (68.90) | |
| ≤ 2 h | 1,732 (38.30) | 1,081 (44.50) | 651 (31.10) | |
| Spherical equivalence (D) | −2.18 ± 3.30 | −2.53 ± 2.57 | –1.76 ± 3.96 | <0.001 |