title: Multifocal VEP provide electrophysiological evidence of predominant dysfunction of the optic nerve fibers derived from the central retina in Leber's hereditary optic neuropathy.
abstract: OBJECTIVE
  To differentiate the bioelectrical cortical responses driven by axons from central and mid-peripheral retina in Leber's hereditary optic neuropathy (LHON) by using multifocal visual evoked potentials (mfVEP).
  
  
  METHODS
  Seventeen genetically confirmed LHON patients (33.35 ± 8.4 years, 17 eyes) and 22 age-matched controls (C) (38.2 ± 6.0 years, 22 eyes) were studied by mfVEP and optical coherence tomography. MfVEP P1 implicit time (P1 IT, ms) and response amplitude density of the N1-P1 components (N1-P1 RAD, nV/deg(2)) of the second order binary kernel were measured for five concentric retinal areas between the fovea and mid-periphery: 0-20 degrees (R1 to R5).
  
  
  RESULTS
  Mean mfVEP P1 ITs and N1-P1 RADs at all five foveal eccentricities were significantly different (p < 0.01) in LHON when compared to controls. In both groups, mean mfVEP responses obtained from R1 to R5 showed a progressive shortening of P1 ITs (linear fitting, LHON: r  = -0.95; C: r = -0.98) and decrease of N1-P1 RADs (exponential fitting, LHON: r (2) = 0.94; C: r (2) = 0.93). The slope of the linear fitting between mean mfVEP P1 ITs in the two groups was about three times greater in LHON than in controls (LHON: y = -13.33x +182.03; C: y = -4.528x +108.1). MfVEP P1 ITs detected in R1 and R2 (0-5 degrees) were significantly correlated (p < 0.01) with the reduction of retinal nerve fiber layer thickness of the temporal quadrant.
  
  
  CONCLUSIONS
  MfVEP identifies abnormal neural conduction along the visual pathways in LHON, discriminating a predominant involvement of axons driving responses from the central retina when compared to those serving the mid-peripheral retina.
authors.affiliation: Neurophthalmology Unit, Fondazione G.B. Bietti- IRCCS, Via Livenza 3, 00198, Rome, Italy, luxzic@hotmail.com.
authors.forename: Lucia
authors.initials: L
authors.lastname: Ziccardi
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Parisi
authors.forename: Daniela
authors.initials: D
authors.lastname: Giannini
authors.forename: Federico
authors.initials: F
authors.lastname: Sadun
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: De Negri
authors.forename: Piero
authors.initials: P
authors.lastname: Barboni
authors.forename: Chiara
authors.initials: C
authors.lastname: La Morgia
authors.forename: Alfedo A
authors.initials: AA
authors.lastname: Sadun
authors.forename: Valerio
authors.initials: V
authors.lastname: Carelli
mesh_terms: D000328:Adult; D001369:Axons / Q000473:pathology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D029242:Optic Atrophy, Hereditary, Leber / Q000175:diagnosis / Q000503:physiopathology*; D012164:Retinal Diseases / Q000175:diagnosis / Q000503:physiopathology*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology; D014793:Visual Cortex / Q000503:physiopathology; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology; D014795:Visual Pathways / Q000503:physiopathology*; D055815:Young Adult