VISUAL HALLUCINOSIS - THE MAJOR CLINICAL DETERMINANT OF DISTORTED CHROMATIC CONTOUR PERCEPTION IN PARKINSONS-DISEASE

Recently distorted chromatic contour perception has been demonstrated in Parkinson's disease (PD). The aim of our study is to determine the clinical factors which influence chromatic contour perception in PD. C hromatic and achromatic contour perception, colour discrimination and clinical data were evaluated in 73 patients with PD. We used a compute r-aided method to determine the chromatic fusion time (CFT) which indi cates the acuity of monochromatic contour perception. Chromatic CFT wa s generally shortened in patients as compared to controls (p <0.01). w hereas achromatic CFT was not significantly different. Variance analys is revealed the ability of colour discrimination and the risk of visua l hallucinations as statistically significant (p <0.05) variables infl uencing contour perception of certain stimuli. In contrast, disease st age, disease duration and disease severity have no relevant effect on chromatic contour perception in Parkinson's disease. On the basis of t hose properties one may suggest that distorted chromatic contour perce ption is due to an impairment at a central stage of visual processing in PD and an imbalance of the serotonergic system. Whether CFT is a re liable method to predict the individual risk of hallucinosis in PD has to be evaluated.