Heredoataxia (spinocerebellar degeneration), ERG alterations, temporal aspects.

Electroretinographic recordings with 'implicit time' study of 6 patients with different forms of heredoataxia and without clinical ophthalmologic abnormalities were done. ERG showed diminished photopic amplitude of the 'b' wave with delayed photopic 'implicit time' in the presence of increased scotopic latencies. The retinal temporal dysfunction of the ERG in heredoataxia is probably a constant feature. Because the ERG registration, with amplitude and 'implicit time', is required for precise diagnosis, the constant association between retinal alteration and heredoataxia has probably been missed in the past.