Decreased color discrimination and contrast sensitivity in Parkinson's disease

Patients with Parkinson's disease (PD) often complain of blurred vision or even of distinctive visual disturbances like hallucinations and illusions. Recent studies have emphasized the potential influence of primary visual de ficits of color and contrast discrimination. To study primary visual functi on, we studied color discrimination (CD) and contrast sensitivity (CS) duri ng 'on' medication in PD patients and compared them to non-PD subjects. Twe nty one PD patients were compared to 30 age-matched controls using CD teste d by the D-15 Lanthony test (D15) and the Farnsworth-Munsell 100 Hue test ( FM) and CS tested by the Pelli-Robson (PL) and the Vis-Tech tables (VT). We excluded subjects with a visual acuity less than or equal to 0.6 Snellen f raction or known ophthalmological diseases. PD patients showed greater impa irment on all visual tests than controls. This difference was significant f or the FM test (P<0.001), the spatial frequencies 12 and 18 cpd (cycles per degree) of the VT test (P<0.05) and both the monocular and binocular PR te sts (P<0.05). Most tests for CS and CD showed statistical independency. CS deficits, but not CD deficits, correlated with age in both patients and con trols. This study documents major and independent impairment of both color and contrast discrimination in PD patients. Further studies should elucidat e possible clinical implications and correlations, such as the frequency of falls or visual hallucinations. (C) 2000 Elsevier Science B.V. All rights reserved.