Oculomotor impairments in de novo Parkinson’s disease

Published on November 9, 2022

Just like a detective searching for clues, scientists are on the hunt for reliable indicators to evaluate Parkinson’s disease. In a recent study, researchers focused on oculomotor performance, the coordination of eye movements, in newly diagnosed, drug-naïve patients. By comparing the oculomotor abilities of Parkinson’s patients, essential tremor patients, and healthy controls, they discovered that both Parkinson’s and essential tremor patients had impaired saccadic latency (the time it takes to start an eye movement) and saccadic accuracy. Additionally, Parkinson’s patients exhibited decreased smooth pursuit eye movement gain at different frequencies. Interestingly, there was no significant difference in oculomotor parameters between the two patient groups. The study also revealed a correlation between prolonged saccadic latency and longer disease duration, as well as decreased smooth pursuit eye movement gain and more severe motor symptoms in Parkinson’s patients. These findings suggest that oculomotor impairments could serve as potential indicators of disease progression in Parkinson’s patients. If you’re curious to learn more about how studying eye movements can provide insights into Parkinson’s disease, check out the full article!

ObjectiveReliable electrophysiological indicators are urgently needed in the precise evaluation of Parkinson’s disease (PD). It is still elusive whether oculomotor performance is impaired or has clinical value in early PD. This study aims to explore oculomotor performance in newly diagnosed, drug-naïve PD and its correlation with clinical phenotype.MethodsSeventy-five patients with de novo PD, 75 patients with essential tremor (ET), and 46 gender-and age-matched healthy controls (HCs) were included in this cross-sectional study. All subjects underwent oculomotor test via videonystagmography. Visually guided saccade latency, saccadic accuracy and gain in smooth pursuit eye movement (SPEM) at three frequencies of the horizontal axis were compared among the three groups. Patients with PD also received detailed motor and non-motor evaluation by serial scales. The association between key oculomotor parameters and clinical phenotypes were explored in PD patients.ResultsBoth de novo PD and ET patients showed prolonged saccadic latency and decreased saccadic accuracy relative to HCs. SPEM gain in PD was uniformly reduced at each frequency. SPEM gain at 0.4 Hz was also decreased in ET compared with HCs. However, there was no significant difference of oculomotor parameters between de novo PD and ET patients. Furthermore, prolonged saccadic latency was correlated with long disease duration, whereas decreased SPEM gain was associated with severe motor symptoms in de novo PD patients.ConclusionOcular movements are impaired in de novo, drug naïve PD patients; these changes could be indicators for disease progression in PD.

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