Quantitative analysis of ocular movements in Parkinson's disease.

In the present study, oculomotor abnormalities were investigated in 24 patients with idiopathic Parkinson's disease. Pursuit gain, slow and fast phase velocity of optokinetic nystagmus (OKN), saccade latency, amplitude and velocity, as well as vestibulo-ocular reflex (VOR) gain were quantitatively analyzed. Twenty-one out of 24 patients showed some abnormalities in their ocular movement. A reduction in pursuit gain, impaired OKN and a significantly increased saccade latency were observed in 11 patients. In 12 patients, hypometric saccade was seen, while a decrease in saccade velocity was observed in 10 patients. All patients registered normal values for VOR gain. Only one patient who had impaired smooth pursuit and decreased saccade velocity before treatment with a dopaminergic drug showed a remarkable improvement in these ocular abnormalities after treatment. These results suggest the possibility of dopaminergic control on these ocular movements.