Ophthalmic features of spinocerebellar ataxia type 7

Eye (Lond). 2018 Jan;32(1):120-127. doi: 10.1038/eye.2017.135. Epub 2017 Aug 11.


PurposeTo analyze the relation between ophthalmologic and motor changes in spinocerebellar ataxia type 7 (SCA7).Patients and methodsThis was a case series study. Sixteen SCA7 patients underwent a comprehensive ophthalmic examination, including ocular extrinsic motility testing, color vision test, and optical coherence tomography of the optic nerve and macula. Changes in the corneal endothelium, electroretinographic patterns, and a complete neurologic evaluation using the Scale for the Assessment and Rating of Ataxia (SARA) were evaluated. Correlations of endothelial cell density (ECD) with number of CAG repetitions and the SARA scores were estimated.ResultsAll patients showed various degrees of visual impairment mainly due to macular deterioration. Notably, they also presented decreased ECD. Pairwise correlations of ECD with number of CAG repeats and severity of motor symptoms quantified with the SARA scores were inverse (r=-0.46, P=0.083 and r=-0.64, P=0.009, respectively). Further analyses indicated an average ECD decrease of 48 cells/mm2 (P=0.006) per unit of change on the number of CAG repeats, and of 75 cells/mm2 (P=0.001) per unit of change on the SARA scores.ConclusionsThe results agree with previous ophthalmological findings regarding the widespread effect of SCA7 mutation on the patient's visual system. However, the results also show a significant negative correlation of decreased ECD with both CAG repetitions and SARA scores. This suggests that motor systems could degenerate in parallel with visual systems, although more research is needed to determine whether the degeneration is caused by the same mechanisms.

MeSH terms

  • Adult
  • Aged
  • Anterior Eye Segment / diagnostic imaging*
  • Color Vision*
  • Corneal Topography
  • Electroretinography
  • Eye Diseases / diagnosis*
  • Eye Diseases / etiology
  • Eye Diseases / genetics
  • Female
  • Humans
  • Male
  • Middle Aged
  • Severity of Illness Index
  • Spinocerebellar Ataxias / complications*
  • Spinocerebellar Ataxias / diagnosis
  • Spinocerebellar Ataxias / genetics
  • Tomography, Optical Coherence
  • Visual Acuity*
  • Young Adult