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Xinxing Guo, Min Fu, Juan Lü, Qixia Chen, Yangfa Zeng, Xiaohu Ding, Ian G. Morgan, Mingguang He; Normative Distribution of Visual Acuity in 3- to 6-Year-Old Chinese Preschoolers: The Shenzhen Kindergarten Eye Study. Invest. Ophthalmol. Vis. Sci. 2015;56(3):1985-1992. doi: https://doi.org/10.1167/iovs.14-15422.
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© ARVO (1962-2015); The Authors (2016-present)
To document the distribution of uncorrected visual acuity (UCVA) in a defined population of Chinese preschoolers and to discuss its implications for vision referral.
Preschoolers aged 3 to 6 years old were recruited from kindergartens in Shenzen. Uncorrected visual acuity was estimated by using Early Treatment Diabetic Retinopathy Study Tumbling E charts, followed by cycloplegic refraction and ocular examination. The reference population was defined as children without clinically significant ocular abnormalities, with spherical equivalent refraction greater than −0.50 to less than +2.00 diopters (D), astigmatism less than 0.75 D, and anisometropia less than 2.00 D. The age-specific UCVA cutoffs were defined by the line where the single-sided 95th percentile of the reference population fell.
A total of 483 of the 1255 children enrolled were considered the reference population. The monocular UCVA cutoff fell on the line of 20/63 at age 3, 20/50 at age 4, and 20/40 at ages 5 and 6. Using no better than these lines as criteria generated referral rates of 9.4% to 27.8% in the general population at different ages, and detected 83.3% and more than 90.0% of those with myopia and amblyopia, respectively. Using uncorrected interocular difference of two or more lines referred 3.6% to 4.3% of the population but identified only approximately 20.0% of those with amblyopia.
Visual acuity is still developing in preschoolers even at age 6. Most children with myopia and amblyopia can be identified with age-specific, monocular UCVA cutoffs in vision screening using Tumbling E charts, with tolerable false-positive rates. Further studies are needed to define the age at which children without significant refractive errors reach 20/20 UCVA.
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