Electroretinograms and visual evoked cortical potentials in Parkinsonian patients with or without L-Dopa treatment

Abstract

Two groups of patients affected by Parkinson's disease (PD) were studied by electroretinography during dark adaptation (AERG) and visual evoked potentials (VEPs): nine patients had never been treated before and 31 were on therapy with L-Dopa plus Carbidopa. A significant reduction in amplitude of the ‘b₁’ wave and ‘a’ wave and a significant delay of P₁ wave with reduction of N₁-P₁ amplitude in VEPs were observed in both groups. A relationship between AERG and VEP alterations was found only in the group of patients treated with L-Dopa plus Carbidopa (p<0.02) and in the total group (p<0.05). Moreover, the degree of electrophysiological abnormalities was neither related to the severity of disease, nor to the duration of therapy and dosage. Retinal dysfunction in PD may be related to neurotransmitter abnormalities observed in this condition.

Key Words:

• Parkinson's disease (PD)
• electroretinogram during dark adaptation (AERG)
• visual evoked potential (VEP)
• dopamine