Objective: To identify and measure how eye movements differ between biallelic PARK2 carriers, carriers of a single PARK2 variant and non-carriers using structured and unstructured eye tracking paradigms.

Background: Mutations in PARK2 are responsible for early-onset Parkinson’s disease (PD) with an average age at onset of 33 in biallelic carriers. PARK2 autopsy studies revealed restricted neurodegeneration within the substantia nigra pars compacta (SNpc) when compared with the more widespread SNpc involvement in idiopathic PD, which may impact the topography of striatal denervation between these two groups [1]. There is conflicting literature regarding how carriers of a single mutation are clinically affected, if at all. Eye movements can be an objective, noninvasive tool to examine PD symptom duration and subtype, however the literature regarding PARK2 mutation carriers and whether their clinicopathologically distinct presentation is reflected in their eye movements is sparse.

Method: A cohort of 50 affected PARK2 carriers, unaffected carriers with a single PARK2 mutation and gene-negative young-onset PD controls attended for data collection. Each participant completed a visually-guided pro- and anti-saccade task and a free-viewing paradigm to assess unstructured eye movements in an ecological setting. Data was collected using the video-based Eyelink 1000+ eye tracker on saccades, blinks and pupil activity. Clinical data was collected in parallel using Movement Disorders Society – United Parkinson’s Disease Rating Scale, Non Motor Symptoms Scale, Beck’s Depression Inventory, Beck’s Anxiety Inventory, Parkinson’s Disease – Q39 and Montreal Cognitive Assessment.

Results: We found that oculomotor behaviour differed between the PARK2 and gene-negative groups, which may relate to their differing pathophysiology and distribution of neurodegeneration.

Conclusion: This study offers a window into how regions of the striatum influence different aspects of eye movements, with future potential to further interrogate movement control differences between these two groups.

References: [1] Doherty KM, Silveira-Moriyama L, Parkkinen L, Healy DG, Farrell M, Mencacci NE, et al. Parkin Disease: A Clinicopathologic Entity? JAMA Neurol. 2013 May 1;70(5):571–9.

« Back to 2025 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/oculomotor-differences-in-park2-pd-a-study-of-structured-and-unstructured-eye-movements-in-an-irish-genetic-cohort/