POOR VISUAL-DISCRIMINATION AND VISUAL HALLUCINATIONS IN PARKINSONS-DISEASE

This study examined the relationship between deficits in color and con trast discrimination and visual hallucinations (VH) in patients with P arkinson's disease (PD) and normal visual acuity. Thirty-five nondemen ted and nonpsychotic PD patients with normal visual acuity and without major ophthalmologic disease were interviewed twice and divided into two groups: hallucinators (n = 14) and non-hallucinating controls (n = 21). The groups were compared for color vision (assessed by Lanthony D-15 [LD] and Farnsworth-Munsell 100 hue [FM] tests), and for contrast sensitivity (tested by Vis tech tables [VT] and monocular and binocul ar Pelli-Robson test [PR]). There was no difference in age, duration o r stage of PD, or dosage or duration of levodopa therapy between the t wo groups. Parkinson's disease patients showed impairment on all visua l tests, with the hallucinators performing worse than the controls on all tests. This difference was significant for the LD (p<0.007), the V T at 1.5 and 3 cycles per degree (p<0.037 and 0.043, respectively) and the monocular PR tests (p<0.049). The results led the authors to conc lude that in patients with normal visual acuity, those with VH show ad ded visual deficits of color and contrast discrimination. These ophtha lmopathies may therefore be facilitating factors for visual hallucinat ions in PD and justify more focused research on the pathophysiology of visual hallucinations in Parkinson's disease.