Ophthalmologic findings in patients with ataxia

To determine the frequency and spectrum of ophthalmologic findings in a large, heterogeneous group of patients with ataxia.

Medical records of 184 patients from a university-based ataxia clinic were retrospectively reviewed. Patients were classified as having Friedreich's ataxia, spinocerebellar degeneration, cerebellar degeneration, familial or sporadic olivo-pontocerebellar atrophy, multisystem atrophy, spastic ataxia, myoclonic ataxia, or other diagnoses such as mitochondrial myopathy. All had complete ophthalmologic examinations, and 107 underwent electro-oculography.

Among 184 patients with ataxia, diplopia was present in 52 (28%), best-corrected visual acuity was decreased in 29 (16%), and oscillopsia was present in 10 (5%). Diplopia was usually caused by an intermittent, small-angle heterotropia. The reduction in best-corrected visual acuity varied from mild to profound and was caused by optic atrophy, retinal degeneration, or both. Optic atrophy was present most frequently in spastic ataxia (five of 22 patients) and myoclonic ataxia (two of eight patients), followed by Friedreich's ataxia (three of 26 patients). Retinal degeneration and ophthalmoplegia were most characteristically associated with familial olivopontocerebellar atrophy and mitochondrial myopathy. Laboratory testing of ocular motility showed frequent abnormalities in all groups. Fixation instability was most characteristic of Friedreich's ataxia, whereas saccadic slowing was noticeably absent from patients with purely cerebellar degenerations.

The ataxias may be associated with visual dysfunction caused by retinal degeneration, optic atrophy, oculomotor disturbance, or a combination of these.