title: Optical coherence tomography differs in neuromyelitis optica compared with multiple sclerosis.
abstract: BACKGROUND
  Neuromyelitis optica (NMO) is associated with destructive inflammatory lesions, resulting in necrosis and axonal injury. Disability from multiple sclerosis (MS) is due to a combination of demyelination and varying axonal involvement. Optical coherence tomography (OCT), by measuring retinal nerve fiber layer (RNFL) as a surrogate of axonal injury, has potential to discriminate between these two conditions.
  
  
  METHODS
  Included were 22 subjects with NMO or NMO spectrum disorders and 47 with MS. Seventeen subjects with NMO and all with MS had a remote history of optic neuritis (ON) in at least one eye, at least 6 months before OCT. Linear mixed modeling was used to compare the two diagnoses for a given level of vision loss, while controlling for age, disease duration, and number of episodes of ON.
  
  
  RESULTS
  After ON, NMO was associated with a thinner mean RNFL compared to MS. This was found when controlling for visual acuity (56.7 vs 66.6 microm, p = 0.01) or for contrast sensitivity (61.2 vs 70.3 microm, p = 0.02). The superior and inferior quadrants were more severely affected in NMO than MS.
  
  
  CONCLUSIONS
  Optic neuritis (ON) within neuromyelitis optica (NMO) is associated with a thinner overall average retinal nerve fiber layer compared to multiple sclerosis, with particular involvement of the superior and inferior quadrants. This suggests that NMO is associated with more widespread axonal injury in the affected optic nerves. Optical coherence tomography can help distinguish the etiology of these two causes of ON, and may be useful as a surrogate marker of axonal involvement in demyelinating disease.
authors.affiliation: Department of Neurology, Washington University, Box 8111, 660 S. Euclid Ave., St. Louis, MO 63110, USA. naismithr@neuro.wustl.edu
authors.forename: R T
authors.initials: RT
authors.lastname: Naismith
authors.forename: N T
authors.initials: NT
authors.lastname: Tutlam
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: E C
authors.initials: EC
authors.lastname: Klawiter
authors.forename: J
authors.initials: J
authors.lastname: Shepherd
authors.forename: K
authors.initials: K
authors.lastname: Trinkaus
authors.forename: S-K
authors.initials: SK
authors.lastname: Song
authors.forename: A H
authors.initials: AH
authors.lastname: Cross
mesh_terms: D000328:Adult; D000368:Aged; D001284:Atrophy / Q000175:diagnosis / Q000503:physiopathology; D001369:Axons / Q000473:pathology; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000503:physiopathology; D009471:Neuromyelitis Optica / Q000175:diagnosis* / Q000503:physiopathology; D009900:Optic Nerve / Q000473:pathology / Q000503:physiopathology; D011237:Predictive Value of Tests; D012160:Retina / Q000473:pathology* / Q000503:physiopathology; D012165:Retinal Ganglion Cells / Q000473:pathology; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence / Q000379:methods*; D014855:Wallerian Degeneration / Q000175:diagnosis* / Q000503:physiopathology; D055815:Young Adult