MedGen

Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is characterized by progressive cerebellar ataxia and variable findings including pyramidal signs, a dystonic-rigid extrapyramidal syndrome, significant peripheral amyotrophy and generalized areflexia, progressive external ophthalmoplegia, action-induced facial and lingual fasciculations, and bulging eyes. Neurologic findings tend to evolve as the disorder progresses. [from GeneReviews]

Reticular dystrophy is a disorder of protean manifestations occurring in the retinal pigment epithelium (RPE) with little or no involvement of the neurosensory retina. The disorder may be detected at an early age and may be slowly progressive, but the prognosis for visual acuity is good. Abnormalities of dark adaptation and nyctalopia may develop with time. Electrophysiologic testing may show a normal electroretinogram (ERG), subnormal electrooculogram (EOG), and subnormal results of dark adaptation studies (summary by Kingham et al., 1978). [from OMIM]

The clinical electro-oculogram (EOG) is an electrophysiological test of function of the outer retina and retinal pigment epithelium (RPE) in which changes in electrical potential across the RPE are recorded during successive periods of dark and light adaptation. [from HPO]