Purpose: To estimate the normative distribution of uncorrected visual acuity (VA) and interocular difference (IOD) in children aged 5~7-year-old without visually significant ocular abnormalities or refractive errors.

Methods: In a group of children aged 5~7-year-old derived from three independent population-based studies, uncorrected VA was measured as categorical outcome using Early Treatment Diabetic Retinopathy Study (ETDRS) tumbling E visual chart, and refraction was measured by cycloplegic autorefraction. The children, with spherical equivalent between -0.50D to +2,00D, cylinder power < 0.75D, interocular diopter difference < 2.00D and without clinical significant ocular abnormalities, were considered to be eligible. Ocular biometry, height and weight were also recorded in 858 children and their associations with uncorrected VA were analyzed using logistic regressions.

Results: The study included 1362 children aged 5~7-year-old. The proportion of children with uncorrected VA of 20/20, 20/25, 20/32 and 20/40 were 5.7%, 42.9%, 47.9% and 3.6% for 5-year-olds, 33.0%, 55.7%, 10.2% and 0.9% for 6-year-olds, and 48.9%, 43.5%, 6.1% and 0.3% for 7-year-olds. Better uncorrected VA was associated with older age, longer axial length (AL), heavier weight and taller height in the univariate analysis, while only older age remained significant in multivariate analysis.