Table 1.
Subject demographic information.
| Total | Primary | Middle | High School | |
|---|---|---|---|---|
| Number | 522 | 344 | 115 | 63 |
| Age (years) | 11.31 (3.08) | 9.58 (1.91) | 13.55 (1.21) | 16.60 (1.32) |
| Boy (%) | 49.81 | 53.20 | 45.22 | 39.68 |
| BMI † | 18.63 (4.02) | 17.57 (3.48) | 20.08 (4.01) | 21.89 (4.31) |
| Family Income (USD, monthly) | 3132.32 (1382.7) | 3180.3 (1394.15) | 3084.93 (1339.60) | 2885.20 (1394.26) |
| Frequency of seeing an opthalmologist (months) | 4.17 (1.80) | 3.92 (1.80) | 4.62 (1.65) | 4.76 (1.87) |
| Private School (%) | 22.56 | 19.82 | 23.00 | 36.51 |
| Cram School (%) | 62.45 | 64.50 | 66.37 | 44.44 |
| Activity Hours | ||||
| Cram School (hours per day) | 1.98 (1.97) | 2.17 (2.06) | 1.81 (1.83) | 1.11 (1.49) |
| Electronic Devises (hours per day) | 1.94 (1.43) | 1.54 (1.26) | 2.30 (1.36) | 3.43 (1.27) |
| TV (hours per day) | 1.77 (1.16) | 1.83 (1.10) | 1.63 (1.15) | 1.71 (1.41) |
| Study (hours per day) | 3.08 (1.10) | 2.93 (0.97) | 3.26 (1.21) | 3.50 (1.24) |
| Sleep (hours per day) | 7.66 (1.12) | 7.90 (1.11) | 7.29 (0.95) | 7.00 (0.96) |
| Outdoor activities (hours per week) | 3.68 (3.42) | 3.80 (3.19) | 3.65 (4.15) | 3.16 (3.19) |
| Refractive error (D) ‡ | 2.42 (2.13) | 1.95 (1.83) | 3.20 (2.23) | 3.62 (2.54) |
| Myopia Progression (D) (in past year) | 0.50 (0.63) | 0.53 (0.61) | 0.47 (0.74) | 0.42 (0.56) |
| Knowledge | 76.52 (10.22) | 77.18 (9.96) | 75.00 (10.51) | 75.67 (10.92) |
| Onset Age | 8.24 (2.71) | 7.46 (0.18) | 9.46 (2.95) | 10.36 (3.20) |
| Other Eye Disorders | ||||
| Amblyopia | 9.41% | 9.55% | 8.03% | 11.11% |
| Strabismus | 5.69% | 6.27% | 5.36% | 3.17% |
Numbers in parentheses represent ± standard deviation. † Body Mass Index (BMI) is calculated as body mass (in kg) divided by the square of body height (in m) or kg/m2. ‡ Myopia or myopia progression are represented as the absolute value of the spherical equivalent (SE) in dioptres (D). Onset Age is the age at which the schoolchildren were diagnosed with myopia. USD, US dollars. Activities are presented as hours per day except for outdoor activities, which is reported as hours per week. Knowledge is an index range from 1 to 100, a higher score represents better vision care knowledge of the parents.