Objective: To determine the response of latencies and amplitudes of saccadic movements to Levodopa in idiopathic Parkinson’s Disease.

Background: Neurodegeneration in Parkinson’s Disease (PD) increases inhibitory output from the basal ganglia, which affects thalamo-cortical circuits, leading to bradykinesia. As a consequence of the general impairment in the motor functions, impaired eye movements has become an accepted clinical finding in patients with Parkinson’s disease. Abnormal smooth and saccadic pursuit eye movements are seen in up to 75% of PD patients.

Saccades may be hypometric. Smooth pursuit may reveal saccadic pursuits (an equivalent of cogwheeling). There is an increase in errors while performing memory-guided saccades. There are studies showing beneficial effects of dopaminergic treatment on saccades in PD in addition to improvement in limb bradykinesia. However, studies which report no beneficial effect of dopaminergic treatment are also present.

Hence, there is no clear consensus on extraocular movement (EOM) improvement in PD with levodopa treatment.

There is no test to objectively measure the extraocular movement excursions in routine practice. This aspect of PD management needs further research.

Method: We recruited 19 patients with PD and 5 age and sex matched healthy controls for this study. The subjects underwent electrooculographic recordings on a Nihon Kohden EEG machine. The controls underwent a single recording session. The patients were required to be 12 hours off levodopa before the study (research OFF state) and underwent recording at baseline and after achieving ON state after levodopa administration. Horizontal and vertical prosaccades and antisaccades were recorded and their latency and amplitudes were measured.

Results: We analysed the data and found that patients with idiopathic PD had delayed saccadic latency as compared to the controls. In the patient group, both the prosaccadic and antisaccadic latencies were delayed and there was improvement in the latencies as well as the saccadic amplitudes after achieving ON state with levodopa administration.

Conclusion: Our study shows improvement of extraocular movements in patients with idiopathic PD after levodopa administration. This method provides an easy non-invasive approach to objectively measure extraocular movements in patients with PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/response-of-extraocular-movements-in-parkinsons-disease-to-levodopa-an-electrooculographic-perspective/