title: Damage to the optic radiation in multiple sclerosis is associated with retinal injury and visual disability.
abstract: OBJECTIVE
  To determine whether damage to the optic radiation (OR) in multiple sclerosis (MS) is associated with optic nerve injury and visual dysfunction.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Referral center.
  
  
  METHODS
  Ninety referred patients with MS and 29 healthy volunteers.
  
  
  METHODS
  Magnetic resonance imaging indices along the OR were reconstructed with diffusion tensor tractography. Retinal nerve fiber layer thickness and visual acuity at high and low contrast were measured in a subset of the MS group (n = 36).
  
  
  RESULTS
  All tested magnetic resonance imaging indices (fractional anisotropy [FA]; mean, parallel, and perpendicular [lambda( perpendicular)] diffusivity; T2 relaxation time; and magnetization transfer ratio) were significantly abnormal in patients with MS. Mean retinal nerve fiber layer thickness was significantly correlated with FA (r = 0.55; P < .001) and lambda( perpendicular) (r = -0.37; P = .001). The retinal nerve fiber layer thickness in the nasal retinal quadrant was also specifically correlated with FA and lambda( perpendicular) in the synaptically connected contralateral OR. In individuals with less severely damaged optic nerves (mean retinal nerve fiber layer thickness >80 mum), letter acuity scores at 2.5% contrast were correlated with OR-specific FA (r = 0.55; P = .004), lambda( perpendicular) (r = -0.40; P = .04), and magnetization transfer ratio (r = 0.54; P = .01), as well as the fraction of OR volume made up of lesions (r = -0.69; P < .001).
  
  
  CONCLUSIONS
  Fractional anisotropy and lambda( perpendicular) are potentially useful quantitative magnetic resonance imaging biomarkers of OR-specific damage in MS. Such damage is associated with retinal injury and visual disability.
authors: Department of Neurology, The Johns Hopkins University School of Medicine, 600 N Wolfe St, Phipps Bldg, Room B-112, Baltimore, MD 21287, USA. reichd@jhmi.edu
authors: Daniel S
authors: DS
authors: Reich
authors: Seth A
authors: SA
authors: Smith
authors: Eliza M
authors: EM
authors: Gordon-Lipkin
authors: Arzu
authors: A
authors: Ozturk
authors: Brian S
authors: BS
authors: Caffo
authors: Laura J
authors: LJ
authors: Balcer
authors: Peter A
authors: PA
authors: Calabresi
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D005829:Geniculate Bodies / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis*; D009412:Nerve Fibers / Q000473:pathology*; D009900:Optic Nerve / Q000473:pathology*; D020221:Optic Nerve Injuries / Q000175:diagnosis*; D009902:Optic Neuritis / Q000175:diagnosis; D055351:Retinal Neurons / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014786:Vision Disorders / Q000175:diagnosis*; D014792:Visual Acuity / Q000502:physiology*; D014793:Visual Cortex / Q000473:pathology; D014795:Visual Pathways / Q000502:physiology; D055815:Young Adult