Table 1.

Characteristics of students included (study population).

Characteristics	Na	% [OR (95%CI)]b
All participants
Rates
Participation rate	5176	96% [95.5–96.5]
Absence rate	216	4% [3.5–4.5]
Age
Group 1 (6–9 years; 7.9 ± 1.1)	2624	50.7% [49.3–52.1]
Group 2 (10–13 years; 11 ± 0.9)	2552	49.3% [47.9–50.1]
Gender
Male	2573	49.7% [48.3–51.1]
Female	2603	50.3% [48.9–51.6]
Participants with refractive error (RE)
Gender
Male	400	7.7% [7.0–8.4]
Female	446	8.6% [7.9–9.3]
Age
Group 1	335	6.5% [5.8–7.2]
Group 2	511	9.8% [9.0–10.6]
Total
Children with RE	963	18.6% [17.5–19.6]
Corrected	92	1.8% [1.4–2.2]
Under-corrected	25	0.5% [0.3–0.7]
Uncorrected RE	846	16.3% [15.3–17.3]

^aN indicates the number of cases.

^bCase percentage, and in parenthesis, adjusted odds ratio with (95% confidence interval).