Visual acuity in 5–7‐year‐old children: individual variability and dependence on observation distance

Abstract

Accurate measurements of uncorrected binocular and monocular visual acuity were performed in 65 children aged 5-7 years at five viewing distances in the range 0.5-5.0 m by means of the test charts containing widely spaced E stimuli in four orientations. It was found that, in most children of this age, visual acuity (V) changed with test distance, as had been reported previously with older subjects. Visual acuity could be considered as practically independent of observation distance (Vmax-Vmin<or=0.2 decimal units) in <50% of children. The remaining children demonstrated evident distance dependence of visual acuity but the shape of the acuity-distance curve varied. The acuity-distance curve of most children peaked at an intermediate distance (1-2 m), the typical difference Vmax-Vmin being 0.4 decimal units. To explain the existence of an optimal observation distance in the majority of children, a number of developmental and environmental factors could be proposed that adjust the parameters of the visual system to the parameters of operational visual space and prevailing activity.

The Auckland Optotypes: An open-access pictogram set for measuring recognition acuity

“…Acuity is a critical measure of visual function for preschool vision screening (Simons, 1996;Cotter et al, 2015), clinical eye care (Donahue & Baker, 2016), and research (Tsirlin, Colpa, Goltz, & Wong, 2015;Guo et al, 2016). Current acuity measurements are limited by test-retest variability (Beck et al, 2003;Rozhkova, Podugolnikova, & Vasiljeva, 2005), patient's familiarity with letters, the ease or difficulty with which individual letters may be recognized (Strong & Woo, 1985;Ferris et al, 1993;Alexander et al, 1997), and for picture optotypes, copyright limitations. In this study, we report the introduction of an open-access set of unique pictograms.…”