Table 2.
Characteristics of participants with and without myopia (N = 6832)
| Non-myopia (N = 2000) |
Myopia (N = 4832) |
P value | |
|---|---|---|---|
| Grade, median (IQR)#1 | 7 (5, 10) | 10 (8, 13) | < 0.001* |
| Age, median (IQR), year#1 | 8.3 (7.1, 10.4) | 12.4 (9.9, 14.4) | < 0.001* |
| Ethnicity, No. (%)#2 | |||
| Non-Han | 24 (1.2) | 44 (0.9) | 0.352 |
| Han | 1976 (98.8) | 4788 (99.1) | |
| Sex, No. (%)#2 | |||
| Boys | 1104 (55.2) | 2392 (49.5) | < 0.001* |
| Girls | 896 (44.8) | 2440 (50.5) | |
| BMI, median (IQR)#1 | 17.361 (15.278, 20.196) | 18.667 (16.442, 21.083) | < 0.001* |
| Resident, No. (%)#2 | |||
| Village | 874 (43.7) | 2145 (44.4) | 0.600 |
| Urban | 1126 (56.3) | 2687 (55.6) | |
| Parents’ myopia, No. (%)#2 | |||
| None of them is myopia | 1149 (57.5) | 2524 (52.2) | < 0.001* |
| At least one is myopia | 851 (42.5) | 2308 (47.8) | |
| Have any bad writing habits #3 ? No. (%) #2 | |||
| Have little bad writing habit | 787 (39.3) | 1533 (31.7) | < 0.001* |
| Have a kind of bad writing habit | 415 (20.8) | 991 (20.5) | |
| Have two kinds of bad writing habits | 322 (16.1) | 865 (17.9) | |
| Have three kinds of bad writing habits | 308 (15.4) | 841 (17.4) | |
| Have four kinds of bad writing habits | 114 (5.7) | 386 (8.0) | |
| Have five kinds of bad writing habits | 54 (2.7) | 216 (4.5) | |
| Working/Studying time per day, No. (%)#2 | |||
| ≤ 6 h | 526 (26.3) | 529 (10.9) | < 0.001* |
| 6–8 h | 1192 (59.6) | 2492 (51.6) | |
| 8–10 h | 196 (9.8) | 1132 (23.4) | |
| > 10 h | 86 (4.3) | 679 (14.1) | |
| Continuous working/studying time per day, No. (%)#2 | |||
| ≤ 1 h | 496 (24.8) | 643 (13.3) | < 0.001* |
| 1–2 h | 868 (43.4) | 1909 (39.5) | |
| 2–3 h | 439 (21.9) | 1370 (28.4) | |
| > 3 h | 197 (9.9) | 910 (18.8) | |
| Screen time per day, No. (%)#2 | |||
| ≤ 0.5 h | 641 (32.1) | 1092 (22.6) | < 0.001* |
| 0.5–1 h | 849 (42.4) | 1834 (38.0) | |
| 1–2 h | 376 (18.8) | 1184 (24.5) | |
| > 2 h | 134 (6.7) | 722 (14.9) | |
#1: Data was analyzed using non-parametric test
#2: Data was analyzed using Chi-square test
#3: Bad writing habits include ①when reading or writing, the distance between the eyes and the table is less than 33 cm, ②when reading or writing, the distance of the chest from the table is less than the width of a punch, ③when writing, the distance between the hand and the tip of the pen is less than 3.3 cm, ④often tilt your head when reading or writing, ⑤often read or write on your stomach
*: P < 0.05