Objective: To delineate microsaccade dynamics in people with Parkinson’s disease (PD) compared with healthy controls (HC) and to examine their associations with disease-related dysfunction.

Background: Oculomotor abnormalities are a well-recognized feature of PD, yet the behavior and clinical relevance of microsaccades – small, involuntary eye movements that support visual stability – remain insufficiently characterized, and their ability to distinguish patients from healthy individuals or reflect disease severity is not yet established. Clarifying these relationships is essential to determine whether microsaccade‑based measures can serve as quantifiable, non‑invasive biomarkers to support diagnosis and monitor clinical progression.

Method: Microsaccades were recorded during fixation using a high-resolution eye tracker in individuals with early-stage PD and matched HC. Multiple microsaccade features were analyzed and their associations with critical clinical markers were evaluated with ordinal regression models. FDR-adjusted p-values are reported.

Results: Valid trials from 46 participants with PD and 40 HC were analyzed. Increased microsaccade amplitude, distance, and peak velocity were found in PD compared to HC, indicating disruption of network regulation. Higher values of these features were associated with worse episodic memory performance, as reflected in delayed recall component of the MMSE (amplitude: OR=0.48; 95% CI 0.27–0.87; p=0.036, distance: OR=0.45; 95% CI 0.24–0.86; p=0.036, peak velocity: OR=0.56; 95% CI 0.30–0.93; p= 0.053). Higher microsaccade rate was associated with higher Hoehn and Yahr stage (OR= 2.77; 95% CI 1.40–5.47; p=0.014). Microsaccade rate increased across consecutive trials in both groups (PD: β=0.04; p=0.001; HC: β=0.06; p<0.001; mixed-effects models). After adjusting for age, sex, and education, higher median microsaccade amplitude (OR =1.95; 95% CI 1.16–3.55; AUC=0.73), distance (OR=1.87; 95% CI 1.13–3.31; AUC=0.72), and peak velocity (OR=1.76; 95% CI 1.05–3.21; AUC=0.71) showed fair discrimination between PD and HC.

Conclusion: Microsaccades demonstrate distinct alterations in early-stage PD, linked to both cognitive function and disease severity. These findings support their potential value as non-invasive, quantifiable physiological markers of early disease‑related dysfunction and enhance mechanistic understanding of oculomotor and cognitive impairment in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/microsaccade-alterations-and-clinical-correlates-in-parkinsons-disease/