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A. J. simmers, P. Knox, C. V. Hutchinson, T. Ledgeway; Sensitivity to Spatio-Temporal Modulations of First-Order Motion and Different Varieties of Second-Order Motion in Amblyopia. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1842.
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It is well established that amblyopes exhibit deficits in processing first order (luminance) patterns. This is readily manifest by measuring spatio-temporal sensitivity (ie window of visibility) to moving luminance gratings. However the window of visibility to moving second order (texture) patterns has not been systematically studied. To address this issue we measured spatiotemporal contrast sensitivity to first order and several different varieties of second order motion, (modulations of contrast, flicker, size and orientation) to see if these are also impaired relative to normal observers.
Observers judged the motion direction (left vs. right) of grating patterns defined by either first order or second order cues over a 5 octave range of spatial and temporal frequencies. Direction thresholds (monocular) were measured using an adaptative staircase procedure for each pattern, which varied the stimulus amplitude (modulation depth).
Compared to normals amblyopes exhibit substantial differences in their sensitivity profile to first order and second order motion they were especially impaired in extracting the direction of the second-order images
Amblyopes are not only impaired in the processing of first order motion they exhibit both higher thresholds and a much narrower window of visibility to second order images. The visual deficit in amblyopia extends to the processing of a diverse range of complex, higher order cues to movement.
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