Table 3. Intention-to-Treat Analysis of Changes in Incident Myopia and Relevant Ocular Parameters After 1 Academic Year Between the Intervention and Control Groupsa.
| Variableb | Study group, No. (%) | Mean difference (95% CI) | P valuec | |
|---|---|---|---|---|
| Intervention | Control | |||
| All children | 798 (48.9) | 833 (51.1) | NA | |
| Prevalence of myopia | ||||
| Baseline | 96 (12.0) | 105 (12.6) | −0.57 (−19.64 to 18.49) | NA |
| 1 Academic year | 154 (19.3) | 179 (21.5) | −2.19 (−35.50 to 30.93) | NA |
| Incidence of myopia | 58/702 (8.3) | 74/728 (10.2) | −1.90 (−18.72 to 14.91) | >.99d |
| SER, mean (SD), diopter | ||||
| Baseline | 0.63 (1.05) | 0.55 (1.13) | 0.08 (−0.06 to 0.22) | NA |
| 1 Academic year | 0.35 (1.22) | 0.23 (1.30) | 0.04 (−0.06 to 0.13) | NA |
| Change from baseline | −0.28 (0.37) | −0.32 (0.47) | 0.03 (−0.06 to 0.13) | NA |
| Axial length, mean (SD), mm | ||||
| Baseline | 23.10 (0.77) | 23.11 (0.75) | −0.001 (−0.10 to 0.09) | NA |
| 1 Academic year | 23.28 (0.82) | 23.31 (0.80) | −0.03 (−0.06 to 0.01) | NA |
| Change from baseline | 0.17 (0.14) | 0.20 (0.14) | −0.03 (−0.07 to 0.01) | NA |
Abbreviations: NA, not applicable; SER, spherical equivalent refraction.
Children with ocular abnormalities at baseline (n = 37) and follow-up visit (n = 42) were excluded from the analysis. Corresponding figures for unsuccessful cycloplegia were 197 and 125, respectively.
Myopia incidence after 1 academic year was a secondary outcome. The remaining outcomes in this table were exploratory outcomes.
The differences in the prevalence and incidence of myopia were compared by proportional Z tests. Linear regression models assessed the differences between the 2 study groups in the SER and axial length at baseline and at the end of 1 academic year, as well as changes of these variables after 1 academic year (adjusting for the baseline SER or axial length). All analyses took into account the cluster effects within schools.
Bonferroni correction was applied to multiple comparisons for secondary outcomes (physical fitness score and myopia incidence), and the corrected P value was presented.