ACQUIRED COLOR VISION DEFICIENCY IN PARKINSON’S DISEASE

Abstract

Acquired color deficiency in the tritan axis in Parkinson’s disease has already been reported, manifesting itself as impaired performance in various visual tasks. However, its clinical significance has always been controversial. In this study we evaluated the performance of Parkinson s disease patients in Lanthony 15-desaturated clinical test and for the first time, compared it with the standard Farnsworth-Munsell 15-dichotomous test, in order to determine the clinical value of the color vision deficiency in these shorter tests and their relationship with other factors such as age, duration and severity of the disease, and the presence of signs and symptoms of depression and hallucinations. This blind case-control study was performed on 39 definitely diagnosed patients (of which 14 patients were excluded because of confounding variables) and 25 sex and age-adjusted controls in a neurologic referral center. The subjects were selected by consecutive sampling. Eleven patients in Farnsworth-Munsell and 3 patients in Lanthony showed normal function, however, overall patients had significantly weaker performance than controls (P-value=0.003 and 0.000 for FM and Lanthony respectively). The pattern of responses in Lanthony was consistent with a mild tritanomalia and had a significant correlation with the severity of motor signs and symptoms (Spearman coefficient=0.44, P-value=0.027). The weaker correlation of color deficiency with age in patients (Spearman coefficient=0.42) in comparison with controls (Spearman coefficient=0.60) also signifies the role of the pathophysiology of the disease. We concluded that color deficiency is a clinically significant visual dysfunction in patients with Parkinson s disease.