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Indu Vedamurthy, Catherine M. Suttle, Jack A. Alexander, Lisa Asper; Binocular interactions of spatial visual signals in children. Journal of Vision 2005;5(8):799. doi: 10.1167/5.8.799.
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© ARVO (1962-2015); The Authors (2016-present)
Stereoacuity, an index of binocularity, is almost adult-like by five years of age (Fox et al., IOVS, 1986). The purpose of this study was to determine whether binocular summation, another index of binocularity, is mature in children older than five years of age. Binocular summation refers to the superior visual performance with two eyes when compared to one eye alone, and is usually expressed as the ratio of binocular sensitivity to best monocular sensitivity. We assessed monocular and binocular performance for letter acuity, contrast sensitivity and spatial localization tasks in 10 children between 6–13 years of age and 10 adult subjects with normal vision and binocularity. For all tasks, the stimulus duration was 100ms. Letter acuity was assessed using a computer generated E target. The subjects had to identify the orientation of the letter E (four-alternative forced-choice). In the contrast sensitivity task, a Gabor patch was presented in one of two temporal intervals. The task was to identify the interval in which the Gabor patch was presented (two-alternative forced-choice). In the alignment task, we used three vertically oriented gabor patches. The task was to report whether the middle patch was located to the right or left of the two fixed peripheral patches. Our results demonstrate binocular summation in both letter acuity and contrast sensitivity irrespective of the age groups. Summation ratios did not vary with age in children aged 6–13 years for all three visual functions. The magnitude of binocular enhancement in acuity and contrast sensitivity was similar in children and adults. There was no summation in the alignment task in either age group. Taken together, our results suggest that binocular neural summation of spatial signals mature before six years of age.
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