title: Analysis of the visual system in Friedreich ataxia.
abstract: To use optical coherence tomography (OCT) and contrast letter acuity to characterize vision loss in Friedreich ataxia (FRDA). High- and low-contrast letter acuity and neurological measures were assessed in 507 patients with FRDA. In addition, OCT was performed on 63 FRDA patients to evaluate retinal nerve fiber layer (RNFL) and macular thickness. Both OCT and acuity measures were analyzed in relation to genetic severity, neurologic function, and other disease features. High- and low-contrast letter acuity was significantly predicted by age and GAA repeat length, and highly correlated with neurological outcomes. When tested by OCT, 52.7% of eyes (n = 110) had RNFL thickness values below the fifth percentile for age-matched controls. RNFL thickness was significantly lowest for those with worse scores on the Friedreich ataxia rating scale (FARS), worse performance measure composite Z2 scores, and lower scores for high- and low-contrast acuity. In linear regression analysis, GAA repeat length and age independently predicted RNFL thickness. In a subcohort of participants, 21% of eyes from adult subjects (n = 29 eyes) had macular thickness values below the first percentile for age-matched controls, suggesting that macular abnormalities can also be present in FRDA. Low-contrast acuity and RNFL thickness capture visual and neurologic function in FRDA, and reflect genetic severity and disease progression independently. This suggests that such measures are useful markers of neurologic progression in FRDA.
authors.affiliation: Department of Neurology, University of Pennsylvania Medical School, Philadelphia, PA, USA. SeyerL@email.chop.edu
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Seyer
authors.forename: Kristin
authors.initials: K
authors.lastname: Galetta
authors.forename: James
authors.initials: J
authors.lastname: Wilson
authors.forename: Reiko
authors.initials: R
authors.lastname: Sakai
authors.forename: Susan
authors.initials: S
authors.lastname: Perlman
authors.forename: Katherine
authors.initials: K
authors.lastname: Mathews
authors.forename: George R
authors.initials: GR
authors.lastname: Wilmot
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Gomez
authors.forename: Bernard
authors.initials: B
authors.lastname: Ravina
authors.forename: Theresa
authors.initials: T
authors.lastname: Zesiewicz
authors.forename: Khalaf O
authors.initials: KO
authors.lastname: Bushara
authors.forename: S H
authors.initials: SH
authors.lastname: Subramony
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ashizawa
authors.forename: Martin B
authors.initials: MB
authors.lastname: Delatycki
authors.forename: Alicia
authors.initials: A
authors.lastname: Brocht
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Balcer
authors.forename: David R
authors.initials: DR
authors.lastname: Lynch
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D015350:Contrast Sensitivity / Q000502:physiology; D005260:Female; D005621:Friedreich Ataxia / Q000150:complications*; D006801:Humans; D008297:Male; D008875:Middle Aged; D041623:Tomography, Optical Coherence; D014786:Vision Disorders / Q000175:diagnosis* / Q000209:etiology*; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult