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Purpose: Patients with eye movement disorders most commonly present to the eye clinic with oscillopsia and diplopia. These presentations are often due to autoimmune diseases, such as uveitis and uveitis syndromes, post-infectious, and paraneoplastic diseases. In this study, we aimed to characterize the ocular nystagmus in these patients using a 3D infrared video oculography.

Methods: We prospectively recruited patients with oscillopsia and performed 60-Hz 3-D eye movement recordings of the patients in the primary and eccentric gazes. Of these, 3 patients had autoimmune cerebellar ataxia and no other confounding eye or brain diagnoses. All patients had comprehensive neuro-ophthalmic examination and were consented to perform eye tracking.

Results: We recruited 3 female patients with autoimmune cerebellar ataxia presenting with abnormal visual function (ages 63, 49, 47). Patient #1 presented with diplopia and history of anti-yo positive cerebellar degeneration associated with ovarian cancer. Patient #2 presented with oscillopsia and blurriness and history of anti-GAD-65 positive cerebellar ataxia and stiff person syndrome. Patient #3 presented with diplopia and nystagmus and history of opsoclonus-myoclonus-ataxia syndrome associated with pancreatic mass. Despite subjective changes in visual function, all patients had good visual acuity. Eye movement exam was significant for instability of fixation due to conjugate oscillations of the eyes and gaze-evoked nystagmus on extreme eccentric gazes. They also had abnormal smooth pursuit but full versional eye movement. Eye movement recording during fixation revealed that two patients had 1-2 Hz 3-dimensional conjugate ocular oscillations measuring 1-3 degrees and 3-4 Hz oscillations measuring up to 10 degrees in patient #3. Patient #2 had continuous horizontal square wave jerks. In all patients, the oscillations were the greatest in the vertical dimension. During reflexive saccades, there was some hypermetric overshooting past the target position, consistent with cerebellar ataxia.

Conclusion: Patients with autoimmune cerebellar ataxia often present with symptomatic oscillopsia and diplopia due to impaired gaze control in the cerebellar-brainstem neurocircuit. Infrared oculography in the point-of-care location can rapidly quantify fixation and saccade parameters and can help monitor disease progression or treatment efficacy.