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S. M. Hornik, J. M. Gallardo, R. Blake, R. E. Carr, K. Holopigian; Biological Motion and Grating Detection in Patients With Cone Dystrophy. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5978.
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Patients with retinal diseases have impaired performance on a variety of measures of visual function. Recently, we showed that some patients with retinitis pigmentosa performed within normal limits on a biological motion task at peripheral retinal locations where their performance on other tasks of visual function was impaired. In the current study, we were interested in determining if patients with retinal diseases affecting central vision would perform better on a biological motion task than on other visual tasks.
Patients with inherited progressive cone dystrophy were examined in this study. Cone dysfunction was diagnosed based on reduced visual acuity, color vision abnormalities and local and full-field ERG results. For the patients, visual acuity for the tested eye ranged from 20/30 to 20/250. The results from the patients were compared to those from an age-similar control group. Contrast thresholds for drifting gratings and thresholds for detecting biological motion imbedded in noise were measured using a temporal two-AFC procedure. Thresholds were measured as a function of eccentricity (at the fovea, 6 and 12 degrees temporal retina). Humphrey threshold visual fields and multifocal electroretinograms (ERGs) were also obtained.
At the foveal location, thresholds for drifting gratings and biological motion were either non-measurable or greatly impaired. All patients performed better at the motion tasks at more peripheral locations; for some patients performance was better for biological motion than for grating contrast sensitivity. The visual field thresholds also showed less impairment at more peripheral locations. The multifocal ERG responses were unmeasurable at many locations where the psychophysical measures were measurable and, in some cases, within normal limits.
The patients with cone dystrophy showed impairment on all of our measures with foveal viewing. At more peripheral locations, some patients performed well on the biological motion task. This implies that performance on this task may involve some higher-order processing that is not assessed with more traditional measures of visual function.
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