Table 1.
Description of myopia and nonmyopia groups.
| Characteristics | Total (N=13,380) | Myopia group (n=10,785, 80.61%) | Nonmyopia group (n=2595, 19.39%) | P valuea | ||
| Age (years), median (IQR) | 14.63 (13.42-16.31) | 14.78 (13.75-16.46) | 14.05 (13.01-15.60) | <.001 | ||
| BMI (kg/m3), median (IQR) | 21.5 (18.9-25.3) | 21.4 (18.9-25.2) | 21.6 (18.8-25.7) | .47 | ||
| Gender, n (%) | <.001 | |||||
|
|
Male | 6803 (50.84) | 5237 (48.56) | 1566 (60.35) | N/Ab | |
|
|
Female | 6577 (49.16) | 5548 (51.44) | 1029 (39.65) | N/A | |
| Nationality, n (%) | .63 | |||||
|
|
Han nationality | 12,004 (89.72) | 9683 (89.78) | 2321 (89.44) | N/A | |
|
|
Other nationalities | 1376 (10.28) | 1102 (10.22) | 274 (10.56) | N/A | |
| School type, n (%) | <.001 | |||||
|
|
Junior | 7850 (58.67) | 6031 (55.92) | 1819 (70.10) | N/A | |
|
|
Senior | 5530 (41.33) | 4754 (44.08) | 776 (29.90) | N/A | |
| Place of origin, n (%) | <.001 | |||||
|
|
Urban area | 5245 (39.20) | 4406 (40.85) | 839 (32.33) | N/A | |
|
|
Suburban area | 8135 (60.80) | 6379 (59.15) | 1756 (67.67) | N/A | |
| Exposure time (years), n (%) | <.001 | |||||
|
|
1 | 4571 (34.16) | 3507 (32.52) | 1064 (41.00) | N/A | |
|
|
2 | 4451 (33.27) | 3581 (33.20) | 870 (33.53) | N/A | |
|
|
3 | 4358 (32.57) | 3697 (34.28) | 661 (25.47) | N/A | |
| Position of trees, n (%) | <.001 | |||||
|
|
From buildings with a small space | 4857 (36.30) | 4018 (37.26) | 839 (32.33) | N/A | |
|
|
From buildings with a large space | 8523 (63.70) | 6767 (62.74) | 1756 (67.67) | N/A | |
aAge and the BMI were reported with P values in the Wilcoxon test. Other variables were reported with P values in the chi-square test.
bN/A: not applicable.