Two patients with spinocerebellar ataxia type 7 presenting with profound binocular visual loss yet minimal...

Two patients with genetically confirmed spinocerebellar ataxia type 7 (SCA7) presented with progressive visual loss. Examination disclosed substantial visual acuity loss, central scotomas, and marked dyschromatopsia. Ophthalmoscopic abnormalities were subtle, with only mild retinal artery attenuation and minimal foveal region pigmentary abnormalities. Both patients had slow saccades and partially limited ductions, although neither reported diplopia. One patient had obvious extremity and gait ataxia, but the other had only an unsteady tandem gait. Results of electroretinography (ERG) were abnormal in both patients. These cases illustrate that SCA7 may present with profound visual loss yet minimal ophthalmoscopic findings and sometimes minimal ataxia. The clues to diagnosis are the abnormal color vision, retinal artery attenuation, abnormal eye movements, and a family history of similar manifestations, which may have gone undiagnosed. Full-field or multifocal ERG will always disclose photoreceptor dysfunction. Genetic testing is now available to confirm the diagnosis.