Treatment for Parkinson’s disease (PD)-associated oculomotor dysfunction has not been adequately studied, and a potential unmet clinical need remains.

Previous studies suggest that smooth pursuit eye movements (SPEMs) are not directly influenced by the dopaminergic system.

Our study investigated the effects of the nondopaminergic drug istradefylline on SPEM in patients with PD.

Istradefylline ameliorated SPEM in PD during the ON state, although differences in somatomotor performance before and after istradefylline treatment were not significant during the ON state.

The discrepancy observed between the oculomotor and somatomotor responses to istradefylline supports previous findings that SPEM is at least partially under nondopaminergic control.