Patient-Reported Visual Function in Ataxias and Association with Clinical Oculomotor Findings

Oculomotor dysfunction is common in ataxias, but its impact on patient-reported visual function remains insufficiently understood. To characterize patient-reported visual function across ataxias and assess the functional significance of specific oculomotor abnormalities in spinocerebellar ataxias. Participants were recruited at Massachusetts General Hospital (n = 117): 56 with genetically-defined ataxias (SCA2, SCA3, SCA6, SCA27B, CANVAS), and 61 controls. Patient-reported visual function was assessed using a 13-item subset of the Visual Activities Questionnaire targeting depth perception, visual acuity/spatial vision, and visual processing speed. Clinical oculomotor assessments focused on four domains: abnormal eye movements at rest, gaze-evoked nystagmus, ocular pursuit abnormalities, and dysmetria of saccades. 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. All ataxia groups reported significantly worse visual function than controls, with the largest deficits in visual processing speed. Compared with age-matched controls, SCA3 and SCA6 individuals had significantly greater functional impairment across all subcategories. In ataxias, visual function correlated moderately with PROM-Ataxia and weakly with clinical oculomotor scores. Gaze-evoked nystagmus was the only oculomotor sign independently associated with reduced visual function. Ataxias are associated with substantial visual impairment, particularly in visual processing speed. Gaze-evoked nystagmus predicts reduced visual function in ataxias, highlighting the functional relevance of fixation instability. Patient-reported measures of visual function and oculomotor assessments are essential for capturing visual disability in clinical care and trials.