Visual acuity in 5-7-year-old children: individual variability and dependence on observation distance.
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.
Rozhkova
Galina I
GI
Institute for Information Transmission Problems, Russian Academy of Sciences, Bolshoi Karetnyi per., 19, 127994 Moscow, Russia. gir@iitp.ru
Podugolnikova
Tatiana A
TA
Vasiljeva
Nadezhda N
NN
D000375:Aging / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D016002:Discriminant Analysis; D005260:Female; D006801:Humans; D008297:Male; D011601:Psychophysics; D012016:Reference Values; D015203:Reproducibility of Results; D014787:Vision Tests / Q000379:methods; D015348:Vision, Binocular / Q000502:physiology; D015349:Vision, Monocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology*