EYE movement abnormalities in Parkinson's disease: optometric screening and rehabilitation.

Background: Parkinson's disease (PD) is increasingly recognized as a multisystem disorder in which eye movement abnormalities provide important diagnostic and prognostic insights. Objective: This review synthesizes current evidence on oculomotor disturbances in PD, their clinical relevance, and their potential as biomarkers for early detection and disease monitoring. Methods: A structured narrative review was conducted using PubMed, Scopus, and Web of Science databases (up to July 2025). Although a systematic search strategy was applied, findings were synthesized narratively due to heterogeneity in study designs and outcomes. Results: Across studies, PD patients demonstrated prolonged saccadic latency, reduced vergence amplitudes, and impaired smooth pursuit, often correlating with disease severity. Several abnormalities were detectable in early-stage disease, preceding overt motor dysfunction. Interventions such as prisms, vergence exercises, and vision therapy showed potential benefits in alleviating diplopia and improving visual function. Quantitative eye-tracking measures emerged as promising objective biomarkers for disease monitoring. Discussion: Oculomotor assessment offers significant clinical implications, from supporting early diagnosis and differential recognition of parkinsonian syndromes to guiding rehabilitative strategies that enhance visual quality of life. However, heterogeneity of methodologies and limited longitudinal data constrain generalizability. Conclusions: Eye movement abnormalities represent a valuable, underutilized tool in PD care. Standardization of assessment protocols, integration with neuroimaging, and validation through large-scale longitudinal studies are essential to establish oculomotor metrics as reliable biomarkers for clinical practice.