Table 5
Relation between myopia and reported near work
| Africans (n = 2258) | Non-Africans (n = 253) | |||||||
|---|---|---|---|---|---|---|---|---|
| Near work (hours per week) | Non-myopic median (n = 2151) | Myopic median (n = 107) | p Value* | Quality control kappa†‡ (n = 217) | Non-myopic median (n = 219) | Myopic median (n = 34) | p Value* | Quality control kappa†‡ (n = 17) |
| *Wilcoxon’s rank sum test for two unpaired samples. | ||||||||
| †Grouped in intervals of 5 hours, except for the sewing variables which were grouped in intervals of 4 hours (to avoid all values being in the same group). | ||||||||
| ‡Interpretation of kappa values: ≤0.20 = poor agreement, 0.21−0.40 = fair agreement, 0.41−0.60 = moderate agreement, 0.61−0.80 = good agreement, 0.81−1.00 very good agreement (13). | ||||||||
| §Term: holidays weighted 3:1. | ||||||||
| ¶N=106. | ||||||||
| (1) Reading for pleasure | ||||||||
| term | 2 | 2 | 0.312 | 0.56 | 3 | 4.5 | 0.017 | 0.73 |
| holidays | 3 | 3 | 0.978 | 0.53 | 3 | 7 | 0.014 | 0.73 |
| term and holidays§ | 2.3 | 2 | 0.362 | 0.57 | 3 | 5.5 | 0.010 | 0.73 |
| last week (term time) | 2 | 2 | 0.436 | 0.62 | 2 | 2 | 0.086 | 0.90 |
| (2) Studying | ||||||||
| term | 20 | 20 | 0.624 | 0.53 | 14 | 14 | 0.984 | 0.69 |
| holidays | 15 | 14 | 0.110 | 0.39 | 8 | 7 | 0.387 | 0.64 |
| term and holidays§ | 18.5 | 18 | 0.381 | 0.47 | 12 | 12 | 0.665 | 0.62 |
| last week (term time) | 18 | 15 | 0.438 | 0.36 | 12 | 10.5 | 0.456 | 0.65 |
| (3) Reading for pleasure and studying | 21.8 | 20.8 | 0.344 | 0.34 | 15.8 | 17.5 | 0.540 | 0.35 |
| (4) Television | ||||||||
| term | 3 | 3 | 0.384 | 0.50 | 7 | 8 | 0.521 | 0.56 |
| holidays | 5 | 5 | 0.674 | 0.48 | 14 | 11.5 | 0.799 | 0.72 |
| last week (term) | 3 | 3¶ | 0.628 | 0.48 | 5 | 6.5 | 0.351 | 0.68 |
| (5) Computer | ||||||||
| term | <1 | <1 | 0.463 | 0.45 | 1 | 2 | 0.080 | 1.00 |
| holidays | <1 | <1 | 0.586 | 0.62 | 2 | 3 | 0.120 | 0.81 |
| last week (term) | <1 | <1 | 0.340 | 0.35 | 1 | 1 | 0.232 | 1.00 |
| (6) Sewing | ||||||||
| term | <1 | <1 | 0.331 | −0.01 | <1 | <1 | 0.869 | 1.00 |
| holidays | <1 | <1 | 0.168 | 0.44 | <1 | <1 | 0.778 | 1.00 |
| last week (term) | <1 | <1 | 0.178 | −0.01 | <1 | <1 | 0.422 | 1.00 |
