Research Article
Risk Factors for Incident Myopia among Teenaged Students of the Experimental Class of the Air Force in China
Table 2
Univariate analysis of potential risk factors for incident myopia.
| Risk factor | Incident myopia, % (n) | value (χ2) | |
| Parental myopia | 0 parents | 27.48 (119) | 0.7525 | 0.1330 | 1 parent | 23.68 (18) | 2 parents | 30.77 (4) | Outdoor activity time (per week) | ≥14 h | 17.72 (14) | 0.0063 | 0.0020 | ≥9.33 h to <14 h | 21.66 (34) | <9.33 h | 32.52 (93) | Near-work time (per week) | ≥28 h | 30.62 (128) | 0.0010 | 0.0005 | ≥21 h to <28 h | 12.60 (9) | <21 h | 12.00 (4) | Reading/writing distance | <30 cm | 42.86 (27) | 0.0065 | — | ≥30 cm | 24.84 (114) | Continuous reading/writing for 1 h or more | Seldom or none | 26.64 (69) | 0.8499 | — | Frequently | 27.38 (72) | Age at the start of primary school | >6 years | 25.64 (40) | 0.6452 | — | ≤6 years | 27.60 (101) | Sleep duration (per week) | ≤49 h | 28.57 (90) | 0.3221 | — | >49 h | 24.64 (51) | Dietary bias | One or more | 30.04 (67) | 0.1777 | — | None | 24.75 (74) |
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