Levodopa improves spatial contrast sensitivity in Parkinson's disease

J. T. Hutton, J. L. Morris and J. W. Elias
Parkinson's Disease Research Center, St Mary of the Plains Hospital, Lubbock, TX 79410.

OBJECTIVE--To study the effect of levodopa on the visual contrast sensitivity of patients with Parkinson's disease. DESIGN--Contrast sensitivity of patients was measured before and after levodopa administration. Patient contrast sensitivity was compared with that of normal controls by repeated-measures analyses of variance. SETTING--Parkinson's disease research center associated with private neurology practice. PATIENTS--Fifteen patients with idiopathic Parkinson's disease (eight men, seven women; mean age, 71.8 years) and 22 normal controls (10 men, 12 women; mean age, 68.0 years) volunteered for the study. INTERVENTION--Levodopa/carbidopa (Sinemet). MAIN OUTCOME MEASURE--Change in contrast sensitivity of parkinsonian patients. RESULTS--Following levodopa treatment, the contrast sensitivity of parkinsonian patients improved significantly at the three lowest spatial frequencies tested (0.4, 1, and 2 cycles per degree). CONCLUSIONS--Levodopa improves low-frequency contrast sensitivity in parkinsonian patients. Initially deficient contrast sensitivity in such patients may be restored to near normal levels by levodopa therapy.