Table 2 Distribution of uncorrected, spectacle corrected, presenting, and best corrected visual acuity in each visual acuity group in terms of number, percentage and 95% confidence interval*.

Visual acuity groups	Uncorrected visual acuity	Spectacle corrected visual acuity	Presenting visual acuity	Best corrected visual acuity
20/32 or better in both eyes	5141 (92.7%)	261 (76.6%)	5238 (95.0%)	5473 (98.5%)
	(91.3–94.2)	(71.5–81.8)	(94.0–95.9)	(98.1–99.0)
20/32 or better in one eye	170 (3.4%)	48 (14.7%)	165 (3.3%)	57 (1.1%)
	(2.6–4.1)	(9.9–19.4)	(2.5–4.1)	(0.8–0.15)
20/40 to 20/63 in the better eye	124 (2.1%)	23 (6.6%)	74 (1.3%)	6 (0.1%)
	(1.6–2.7)	(4.1–9.0)	(0.9–1.7)	(0.03–0.23)†
20/80 to 20/160 in the better eye	75 (1.2%)	7 (2.1%)	16 (0.3%)	5 (0.1%)
	(0.6–1.8)	(0.6–3.6)	(0.1–0.5)	(0.05–0.36)†
20/200 or worse in the better eye	25 (0.5%)	–	6 (0.1%)	3 (0.1%)
	(0.2–0.8)		(0.05–0.38)	(0.03–0.35)†
Total sample	5535	339	5544	5544

*Standardised for age and grade level

†The 95% confidence interval was calculated using binominal distribution

The design effect was 0.8 to 4.4