Abstract
BACKGROUND: Oculomotor dysfunction is common in parkinsonian syndromes and ataxias, but its impact on patient-reported vision-related quality of life (VQoL) remains insufficiently understood. OBJECTIVES: To characterize VQoL across parkinsonian syndromes and ataxias and assess the functional significance of specific oculomotor abnormalities in spinocerebellar ataxias. METHODS: Participants were recruited at Massachusetts General Hospital ( n =231): 104 with Parkinson's disease (PD), 10 with progressive supranuclear palsy (PSP), 56 with genetically defined ataxias (SCA2, SCA3, SCA6, SCA27B, CANVAS), and 61 healthy controls. VQoL was assessed using a 13-item subset of the Visual Activities Questionnaire targeting depth perception, visual acuity/spatial vision, and visual processing speed. Clinical severity was assessed with the Brief Ataxia Rating Scale and Modified International Cooperative Ataxia Rating Scale, and subjective symptoms with PROM-Ataxia. Group comparisons, correlations, and regression analyses were performed. RESULTS: All disease groups reported significantly worse VQoL than controls, with the largest deficits in visual processing speed. PSP showed the greatest impairment across all domains, while PD was less affected. Individuals with SCA3 and SCA6 had significantly lower VQoL across all subcategories. In ataxias, VQoL correlated moderately with PROM-Ataxia and weakly with clinical oculomotor scores. Gaze-evoked nystagmus was the only oculomotor sign independently associated with reduced VQoL. CONCLUSIONS: Parkinsonian syndromes and ataxias are associated with substantial VQoL impairment, particularly in visual processing speed. Gaze-evoked nystagmus is a key predictor of reduced VQoL in ataxias, highlighting the functional relevance of fixation instability. Patient-reported outcomes and oculomotor assessments are essential for capturing visual disability in clinical care and trials.