Abstract
Objective: Parkinson's disease (PD) is a neurodegenerative disease characterized by motor impairment alongside prominent cognitive and sensory dysfunction. This review synthesizes converging evidence that oculomotor abnormalities represent an underrecognized clinically meaningful feature of PD and provides insight into how their mechanistic significance may inform a unifying model of global symptomology.

Methods: A narrative review of the literature was conducted to examine evidence regarding oculomotor dysfunction, neural oscillations, rhythmic coordination, ocular biomarkers, and multimodal assessment approaches in PD. Evidence from eye tracking, pupillometry, retinal imaging, electrophysiology, gait analysis, and related neurophysiological studies was integrated to evaluate the potential role of ocular dysfunction within a rhythm-centered framework of PD pathophysiology.

Results: Deficits such as hypometric saccades, impaired smooth pursuit, fixation instability, and vergence insufficiency disrupt visual stability, reading fluency, spatial navigation, and safety, contributing substantially to reduced quality of life and increased fall risk. Oculomotor dysfunction reflects broader disturbances in the temporal organization, regularity, and predictive control of eye movements that may index network-level rhythmic dyscoordination. Abnormal eye movements are closely linked to exaggerated beta-band oscillations and impaired cross-frequency coupling within basal ganglia cortical networks, paralleling rhythmic deficits observed in limb motor control, gait, and cognitive processing. Advances in eye
tracking, pupillometry, and retinal imaging support the potential of ocular measures as noninvasive biomarkers for early detection, disease monitoring, and phenotyping.

Conclusion: Current diagnostic and treatment approaches remain fragmented, and personalization is limited. Integration of multimodal biomarkers, including eye tracking, electrophysiology, gait analysis, and imaging, within longitudinal frameworks is needed to capture shared pathophysiological mechanisms across motor and nonmotor symptoms. Advancing understanding of oculomotor symptomology may support a rhythm-centered model of Parkinson's disease, positioning disrupted temporal coordination as a unifying principle that can inform diagnosis, guide individualized interventions, and improve clinical outcomes.

Key words: Biomarkers, Eye-tracking, Oculomotor dysfunction, Parkinson’s disease, Rhythmic coordination