Progressive worsening of spatial and chromatic processing deficits in Parkinson disease

Context: Impairments of color discrimination (CD) and contrast sensitivity are established signs of Parkinson disease (PD), but their temporal evolution has not been studied. Objective: To determine whether there is progressive, longitudinal deterioration of color discrimination (CD) and contrast sensitivity (CS) in PD. Design: A prospective study. Setting: Tertiary care center-based sample of PD patients without dementia with normal visual acuity (Snellen fraction >0.6 in the best eye). Main Outcome Measures:With a mean +/-SD interval of 19.8 +/- 2.8 months, the following tests were applied twice in 2 patients: the Lanthony D15 test and the Farnsworth Munsell 100 Hue test as tests of CD and the monocular and binocular Pelli-Robson test and the binocular Vistech tables as tests of CS. Results: There was deterioration of both CD (Farnsworth Munsell 100 hue test: P=.002) and CS (binocular. Vistech test at a spatial frequency of 6 cycles per degree, P<.001). Both deficits correlated with age, and the chromatic deficit additionally correlated with higher impairment of motor function (Unified Parkinson's Disease Rating Scale motor section, P=.04) and activities of daily life (Unified Parkinson's Disease Rating Scale activities of daily living section, P=.006). Patients with the highest pathologic psychiatric rating score (Brief Psychiatric Rating Scale) performed worse on both CS (P=.02) and CD (P=.01) at the second examination. Conclusions: Impairments of CD and CS in PD are progressive over time. Visual deficits may influence overall, motor function and lead to enhanced motor impairment.