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Xinxing Guo, Xiaohu Ding, Ian George Morgan, Mingguang He; Normative distribution of visual acuity and interocular difference in 3 to 6 year-old Chinese preschoolers: the Shenzhen Kindergarten Eye Study. Invest. Ophthalmol. Vis. Sci. 2014;55(13):431.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the normative distribution of uncorrected visual acuity (UCVA) and interocular difference (IOD) in a population of Chinese preschoolers without clinically significant ocular abnormalities or refractive errors and to discuss the implications for referral of preschoolers.
Preschoolers aged 3 to 6 years old were recruited from kindergartens in Shenzhen City, China. UCVA and IOD were estimated using Early Treatment Diabetic Retinopathy Study (ETDRS) Tumbling E charts, followed by ocular biometry measurement, cycloplegic autorefraction, as well as detailed ocular examinations. The normative population was defined as children without clinically significant refractive error or ocular abnormalities, whose spherical equivalent (SE) is > -0.50 to < 2.00 diopters (D), < 0.75 D astigmatism and < 2.00 D anisometropia.
Among the 1255 children enrolled, UCVA was successfully collected in 1128 (89.9%) children. Among the 483 children who were classified as the normative population, the single side 95th percentile fell into the UCVA 20/50 category at age 3, 20/40 at age 4, 20/32 at age 5 and age 6. Using these UCVA cutoffs as the criteria would lead to the referral for further examination of 9.4% of children at age 3, 26.2% at age 4, 27.8% at age 5 and 18.6% at age 6 in the general population (N=1128). However, using IOD greater than 1 line as a criterion would generate referral in 3.6% at age 3, 3.7% at age 4, 4.1% at age 5 and 4.3% at age 6 in the general population.
Visual acuity is still developing in preschoolers. Using age-specific 95th percentile as cutoffs for referral may lead to false positives and unnecessary referrals. IOD greater than 1 line may provide a more stable and conservative criterion for referral.
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