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C. E. Donaldson, T. K. Green, V. Dobson, J. M. Miller, D. H. Messer, E. M. Harvey; Radial Hyperacuity in Astigmatic Children. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5279.
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© ARVO (1962-2015); The Authors (2016-present)
Evidence suggests that detection of small levels of modulation in radial hyperacuity stimuli (created by sinusoidally modulating the contour of a circle) requires global pooling of local orientation information (Hess, Wang, Dakin 1999) (Wilkinson, Wilson, Habak 1998). Both strabismic amblyopes (Hess, Wang, Demanins, Wilkinson, Wilson 1999) and children with unilateral deprivation amblyopia (Jeffrey, Wang, Birch 2004) show elevated thresholds for radial hyperacuity in the amblyopic eye. We conducted a pilot study to determine whether young children could reliably perform a radial hyperacuity task and to determine if children with significant astigmatism showed evidence of reduced best-corrected visual performance on the task.
58 kindergarten (K) and 1st grade Tohono O’odham Native American children (mean age 6.8 years, range 5.5 to 8.7 years (SD .79)) were asked to perform a 4AFC radial hyperacuity task. Testing was conducted using the RFSW Shape Discrimination Charts (Yi-Zhong Wang, Copyright 2001-2004). Subjects were tested monocularly (RE) and with spectacle correction. Children with anisometriopia >1.50 D spherical equivalent were excluded. Threshold was determined for stimuli of mean radius of 1.0 deg and 0.5 deg. Each child also completed a cycloplegic eye examination, and refractive error was determined by autorefraction (Nikon Retinomax K+), with sphere verified and refined by retinoscopy as needed.
Results indicated that all 57 K and 1st grade children could be tested successfully with the charts. Children with ≥ 1.00 D of RE astigmatism (n=31) showed poorer thresholds for detection of radial deformation of 0.5 deg stimuli than did children with <1.00 D of RE astigmatism (n=26) (p < 0.05). No significant differences were found for 1.0 deg stimuli.
The data indicate that young children can reliably perform the radial hyperacuity task. Initial pilot data suggest that astigmatism is associated with best-corrected deficits in radial hyperacuity, but that these deficits are only apparent for smaller (0.5 deg) stimuli.
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