Levodopa improves spatial contrast sensitivity in Parkinson's disease.

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.