Altered global shape discrimination in deprivation amblyopia.

To assess the effect of deprivation amblyopia on global shape discrimination, sensitivity to radial deformation of circular patterns was assessed in patients treated for congenital (N=7) or developmental (N=1) cataracts. Elevation in radial deformation threshold was dependent on circular contour frequency and the depth of amblyopia. Analysis of thresholds expressed as Weber fractions indicated a shift in global integration to a larger scale. In a pedestal experiment, equivalent intrinsic noise increased in proportion to the depth of amblyopia. The results suggest neural undersampling in V1 and/or higher visual cortical areas in deprivation amblyopia and a possible role for neural disarray.