Distorted colour discrimination in Parkinson's disease is related to severity of the disease

The Farnsworth-Munsell 100-hue test (FMT) may be used for measurement of colour discrimination and error scores of the FMT provide an unspecific biological marker for the distinction between parkinsonian patients (PP) and healthy controls. The aim of this study was to examine the possible association between distorted colour discrimination and disease severity in untreated "de novo" PP Error scores of the FMT were significantly (P<0.0001) elevated in PP compared to age- and sex-matched controls and correlated to severity of the disease. We conclude that impaired colour discrimination is related to pathophysiology of Parkinson's disease. But it remains unclear whether these alterations of colour vision reflect striatal dopamine deficiency or changes of retinal dopaminergic pathways in PP.