Abstract
Aims: To establish, using the crowded Kay Picture test, the ranges of visual acuity in children aged 42–48 months which are associated with normal and abnormal refractive status. To identify the visual acuity and refractive error distribution in this age group. Methods: Children attending a primary vision screening service had visual acuity measured and cycloplegic refraction undertaken. Refractive error was pre-defined as normal, borderline and abnormal by using existing evidence. On the basis of the refractive error found, visual acuity ranges associated with each refractive group were established. Children with squint and ocular pathology were excluded. Results: Seven hundred and thirty-three children participated, with a median age of 43 months. Ninety per cent had a normal monocular refractive error. Ninety-three per cent of children had insignificant anisometropia. When anisometropia was insignificant, the median (IQR) visual acuity was 0.05 (0.00–0.10) for both right eye and left eye. Median (IQR) interocular visual acuity difference in this group was 0.025 (0.00–0.05). There was a statistically significant difference between the visual acuity ranges for each of the normal, borderline and abnormal refraction groups ( p < 0.001). The median refractive error was þ0.38D spherical equivalent for the right eye and þ0.50D spherical equivalent for the left eye. Conclusion: Children of 42–48 months with monocular visual acuity of equal to or better than 0.10 and with an interocular visual acuity difference of 0.05 or less when tested with the crowded Kay Picture test are likely to have a normal refractive status.
Highlights
Previous research has shown that pre-school children who fail to score 0.00 on visual acuity (VA) testing frequently turn out to have normal refraction
The aim was to define as securely as possible a level of refractive error highly unlikely to result in reduced VA and a level of refractive error highly likely to result in reduced VA
Three hundred and seventy-three (50.8%) children were randomised to right/left eye order of VA testing and 361 (49.2%) to left/right eye order
Summary
Previous research has shown that pre-school children who fail to score 0.00 on visual acuity (VA) testing frequently turn out to have normal refraction. Shea and Gaccon[1] found that the mean monocular acuity for children with normal refraction was 0.20 in 3-year-olds and 0.14 in 4-year-olds, using the Keeler crowded logMAR test. Their cohort was new referrals to the orthoptic department. Jones et al.[4] compared the crowded KP test with the crowded logMAR letter test in children aged 2.5–16 years They found a significant correlation between the VA results of the two tests, with a small, clinically insignificant, difference in the mean acuities. They found that 70% of children below 5 years managed to perform the test successfully, compared with 60% managing the crowded logMAR test
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