title: Axonal loss and myelin in early ON loss in postacute optic neuritis.
abstract: OBJECTIVE
  To investigate the relation between retinal nerve fiber layer (RNFL) thickness and latency and amplitude of multifocal visual-evoked potentials (mfVEPs) in the postacute stage of optic neuritis in patients with early or possible multiple sclerosis.
  
  
  METHODS
  Thirty-two patients with clinical diagnosis of unilateral optic neuritis and magnetic resonance imaging lesions typical of demyelination and 25 control subjects underwent mfVEP and optical coherence tomography imaging.
  
  
  RESULTS
  Although there was significant reduction of RNFL thickness in the affected eyes (18.7%), a considerably larger decrease was observed for the amplitude of the mfVEPs (39.8%). Latency of the mfVEPs was also significantly delayed in optic neuritis eyes. In fellow eyes, the amplitude of mfVEPs was significantly reduced and the latency prolonged, but RNFL thickness remained unaltered. RNFL thickness correlated highly with the mfVEP amplitude (r = 0.90). There was also strong correlation between optical coherence tomography measure of axonal loss and mfVEP latency (r = -0.66).
  
  
  CONCLUSIONS
  Although our findings demonstrate strong associations between structural and functional measures of optic nerve integrity, the functional loss was more marked. This fact, together with amplitude and latency changes of the mfVEPs observed in clinically normal fellow eyes, may indicate greater sensitivity of mfVEPs in detecting optic nerve abnormality or the presence of widespread inflammation in the central nervous system, or both. The significant correlation of the mfVEP latency with RNFL thickness suggests a role for demyelination in promoting axonal loss.
authors.affiliation: Department of Ophthalmology, Save Sight Institute, University of Sydney, Sydney, Australia. sasha@eye.usyd.edu.au
authors.forename: Alexander
authors.initials: A
authors.lastname: Klistorner
authors.forename: Hemamalini
authors.initials: H
authors.lastname: Arvind
authors.forename: Than
authors.initials: T
authors.lastname: Nguyen
authors.forename: Raymond
authors.initials: R
authors.lastname: Garrick
authors.forename: Mark
authors.initials: M
authors.lastname: Paine
authors.forename: Stuart
authors.initials: S
authors.lastname: Graham
authors.forename: Justin
authors.initials: J
authors.lastname: O'Day
authors.forename: John
authors.initials: J
authors.lastname: Grigg
authors.forename: Francis
authors.initials: F
authors.lastname: Billson
authors.forename: Con
authors.initials: C
authors.lastname: Yiannikas
mesh_terms: D000208:Acute Disease; D000328:Adult; D001369:Axons / Q000473:pathology*; D003430:Cross-Sectional Studies; D018450:Disease Progression; D004568:Electrodiagnosis; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009186:Myelin Sheath / Q000473:pathology*; D009410:Nerve Degeneration / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology; D009900:Optic Nerve / Q000473:pathology* / Q000503:physiopathology; D009902:Optic Neuritis / Q000473:pathology* / Q000503:physiopathology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011930:Reaction Time / Q000502:physiology; D012160:Retina / Q000473:pathology* / Q000503:physiopathology; D012165:Retinal Ganglion Cells / Q000473:pathology*; D013997:Time Factors; D041623:Tomography, Optical Coherence