Progressive worsening of spatial and chromatic processing deficits in Parkinson disease

Abstract

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 28 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.