Objective: To evaluate the correlation between oculometric measures (OMs), disease severity, and clinical assessment in a cohort of patients with Parkinson’s disease (PD).

Background: Oculometric measures (OMs) are variables of eye movements detected while performing a task in response to a visual stimulus. Eye movement abnormalities in patients with PD are widely described, and they may reflect the severity of the motor symptoms. However, the use of OMs as an objective biomarker for PD is in its infancy, and knowledge of their correlation with disease severity and clinical assessment is still lacking.

Method: The cohort included 104 patients (35 female) with idiopathic PD (75 H&Y ≤2, 29 H&Y ≥3) of mean age 70.1±7.9 years and 104 age-matched healthy control subjects. Patients were evaluated with the MDS-UPDRS. All study  participants completed a software-based oculometric test with visual stimuli presented on-screen. OMs were extracted using proprietary algorithms. Values were compared between groups using t-test. Pearson correlations were calculated between OMs, MDS-UPDRS motor scores, and disease severity.

Results: Saccadic latency (ms) was longer in patients with high disease severity than in both patients with low disease severity and healthy subjects (pro-saccade: 295.9±80.7 vs. 254.9±57.4 and 233.1±46, respectively, p<0.01; anti-saccade: 411.6±133.3 vs. 350.4±107.8 and 294.9±61.8, respectively, p<0.01) and moderately correlated with MDS-UPDRS motor scores (R=0.4, p<0.01). Error rate (%), defined as the percentage of  times responders looked in the wrong direction, was higher in patients with high disease severity than in both patients with low disease severity and healthy subjects (0.53±0.23 vs. 0.41±0.22 and 0.25±0.21, respectively, p<0.05). Initial gain (%), defined as the accuracy of primary saccadic movement relative to stimulus displacement, was lower in  patients with high disease severity than in the other groups (0.75±0.22 vs. 0.84±0.22 and 0.96±0.15, respectively, p<0.05). Both OMs were correlated with MDS-UPDRS scores (R=-0.39, R=0.24, respectively, p<0.05).

Conclusion: Oculometric deficits of patients with PD are in correlation with disease severity and with MDS-UPDRS motor scores. Using oculometric data can be implemented for assessment of people with PD in future studies, and may serve as a tool to follow disease progress.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/correlation-between-oculometric-measures-disease-severity-and-clinical-assessment-in-patients-with-parkinsons-disease/