Abstract
Purpose: :
Patients with retinitis pigmentosa (RP) may have impaired visual function on a variety of tasks, including spot detection and contrast and motion sensitivity. Typically, the deficits are smallest for central targets and increase with eccentricity. Recently, attention has been focused on issues related to mobility and ‘higher order’ perceptual tasks in these patients. To further study issues of environmental perception, in the current study, we examined the performance of patients with RP on a biological motion task as a function of eccentricity.
Methods: :
Patients with RP and an age–similar control group were tested. The patients with RP had visual acuity of > 20/60 and Goldmann visual fields (V4e) of > 12 degrees. 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) and the size of the targets were scaled to account for cortical magnification factors. Humphrey threshold visual fields and multifocal electroretinograms (mfERGs) were also measured.
Results: :
For the biological motion task, the performance of the patients with RP was equivalent to the control subjects, even for the peripheral locations. In contrast, the patients’ contrast thresholds for drifting gratings were elevated and the amount of threshold elevation increased with increasing eccentricity. The visual field thresholds and mfERG parameters were also impaired and the amount of impairment increased with eccentricity.
Conclusions: :
These results indicate that patients with RP can perform on a biological motion task, even at peripheral locations where threshold measures indicate significant impairment of visual function. This implies that processing for this higher–order task is not affected in these patients with RP.
Keywords: retinal degenerations: hereditary • motion-2D • perimetry