Contrast and Color Sight Gets Worse in Parkinson’s

A DGReview of: “Progressive Worsening of Spatial and Chromatic Processing Deficits in Parkinson Disease.” Archives of Neurology

By Mark Pownall

Defects in the ability to see in color and the visual ability to detect contrasts deteriorate over time in patients with Parkinson’s disease.

A prospective study of 28 Parkinson’s patients without dementia who had normal visual acuity (with a Snellen fraction of more than 0.6 in the better eye) showed progressive worsening of both color vision and contrast sensitivity over about 20 months.

The researchers behind the study say that the visual defects had been linked to Parkinson’s, but there was no previous evidence for a progressive change.

Researchers at Rush-Presbyterian-St Luke’s Medical Center, Chicago, Illinois, United States and the the Centre Hospitalier de Luxembourg, in Luxembourg, measured color vision using the Farnsworth Munsell 100 hue test and the Lanthony D15 tests. Contrast sensitivity was measured using the monocular and binocular Pelli-Robson test and the binocular Vistech tables. The tests were given twice, an average of 19.8 months apart.

The difference between the two readings was statistically highly significant (p=0.002) for color discrimination, and for contrast sensitivity (p<0.001).

Both the visual defects were more common the older patients became, while the color vision deficit was linked to more impairment of motor function and to activities of daily living, as measured by the Unified Parkinson’s Disease Rating Scale.

Patients who were most mentally unhealthy based on answers to a questionnaire (the Brief Psychiatric rating Scale) performed worse on both color vision and contrast sensitivity at the second investigation.

The researchers suggest that “visual deficits may influence overall motor function and lead to enhanced motor impairment.”

Arch Neurol. 2002;59:1249-1252 “Progressive Worsening of Spatial and Chromatic Processing Deficits in Parkinson Disease”

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