The usefulness of eye-tracking tasks as potential biomarkers for motor or cognitive disease burden in Parkinson’s disease (PD) has been subject of debate for many years. Several studies suggest that the performance in the antisaccade task may be altered in patients with PD and associated with motor disease severity or executive dysfunction. In this meta-analysis, random effects models were used to synthesize the existing evidence on antisaccade error rates and latency in PD. Furthermore, meta-regressions were performed to assess the role of motor and cognitive disease severity, dopaminergic medication and methodological factors. Additionally, the impact of acute levodopa administration and activation of deep brain stimulation was evaluated in two separate sub-analyses.This meta-analysis confirms that antisaccade latency and error rate are significantly increased in PD. Disease duration, Unified Parkinson’s disease rating scale score and Hoehn and Yahr stage mediate the effect of PD on antisaccade latency with higher motor burden being associated with increased antisaccade latency.Acute administration of levodopa had no significant effects on antisaccade performance in a small number of eligible studies. Deep brain stimulation in the subthalamic nucleus, on the other hand, may alter the speed accuracy trade-off supporting an increase of impulsivity following deep brain stimulation in PD.According to the results of the meta-analysis, antisaccade latency may provide a potential marker for disease severity and progression in PD which needs further confirmation in longitudinal studies.

Considerable efforts have been made to evaluate different aspects of saccadic eye movements as potential biomarkers in FIG. 1. Findings during the levodopa (L-dopa) challenge test. A drug challenge test was arranged to characterize the nature of the patient's disabling dyskinesia. The patient was given 500 mg oral L-dopa and was monitored closely throughout one dosing cycle. The temporal and topographic pattern of her dyskinesia is characteristic of diphasic dyskinesia in advanced Parkinson's disease. Inhaled L-dopa was explored to address her wearing-off, but we also observed an improvement and shortened duration of her diphasic dyskinesia.