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Table 2 Distribution of uncorrected, presenting, and best corrected visual acuity

From: Prevalence and causes of visual impairment and rate of wearing spectacles in schools for children of migrant workers in Shanghai, China

Visual acuity category Uncorrected visual acuity Wearing glasses* Presenting visual acuity Best visual acuity
n (%; 95% CI) n (%) n (%; 95% CI) n (%; 95% CI)
≥20/32 both eyes 7506 (78.91; 78.09–79.73) 17 (0.23) 7677 (80.71; 79.92–81.50) 9301 (97.78; 97.48–98.08)
≥20/32 one eye only 738 (7.75; 7.21–8.28) 44 (5.96) 764 (8.03; 7.48–8.58) 151 (1.59; 1.34-1.84)
≤20/40 to ≥ 20/63 better eye 887 (9.33; 8.75–9.92) 135 (15.22) 816 (8.58; 8.02–9.14) 43 (0.41; 0.21–0.78)
≤20/80 to ≥ 20/160 better eye 333 (3.50; 3.13–3.87) 102 (30.63) 235 (2.34; 1.59–3.42) 15 (0.14; 0.07 –0.31)
≤20/200 better eye 48 (0.50; 0.33–0.75) 30 (62.5) 20 (0.20; 0.11–0.38) 2 (0.03; 0.004–0.19)
All 9512 (100.00) 328 (3.45) 9512 (100.00) 9512 (100.00)
  1. *The percentage within each visual acuity category is based on uncorrected vision.
  2. Confidence intervals (CIs) were calculated using the exact binomial distribution instead of the normal approximation, and cluster design effects were taken into account in calculating Cls for estimates based on the normal approximation ranging from 1.647 to 6.718.