title: Identifying preperimetric functional loss in glaucoma: a blue-on-yellow multifocal visual evoked potentials study.
abstract: OBJECTIVE
  To determine the ability of blue-on-yellow multifocal visual evoked potentials (BonY mfVEP) to identify functional loss in preperimetric glaucoma.
  
  
  METHODS
  Prospective case series.
  
  
  METHODS
  Thirty patients with glaucomatous optic discs and normal standard visual fields.
  
  
  METHODS
  All patients underwent BonY mfVEP, dilated optic disc stereophotography, and optical coherence tomography (Fast RNFL protocol). Optic disc photographs were assessed by 2 independent examiners in a masked fashion.
  
  
  METHODS
  The mfVEP amplitude asymmetry and latency values were analyzed and compared topographically with findings of disc assessment. Average retinal nerve fiber layer (RNFL) thickness, RNFL asymmetry, and sectors with RNFL thinning were compared between patients with and without mfVEP defects.
  
  
  RESULTS
  Fourteen (46.7%) patients demonstrated significant abnormality on amplitude asymmetry deviation plots of BonY mfVEP. In all 14 cases, the defect was monocular and corresponded to the eye with the worse disc. In 13 of 14 patients, the defect also corresponded to the location of the worst affected rim. Average RNFL thickness of eyes with mfVEP defects was 81.2+/-9.9 microm, significantly lower than that of patients without defects (90+/-10.5 microm; P = 0.035). Mean asymmetry of RNFL (better minus worse eye) also was significantly higher for patients with mfVEP defects compared with those without such defects (9.0+/-6.4 microm vs. 3.0+/-7 microm; P = 0.03). Average latency of both eyes of glaucomatous patients was delayed compared with that of controls, with no difference in latency between worse and better eyes of glaucoma patients. There was no association of latency delay with either the location of disc changes or mfVEP amplitude defects.
  
  
  CONCLUSIONS
  Amplitude asymmetry of the BonY mfVEP seems to be a promising tool to identify functional loss in preperimetric glaucoma.
  
  
  BACKGROUND
  Proprietary or commercial disclosure may be found after the references.
authors.affiliation: Save Sight Institute, University of Sydney, Sydney, Australia. hema@eye.usyd.edu.au
authors.forename: Hemamalini
authors.initials: H
authors.lastname: Arvind
authors.forename: Stuart
authors.initials: S
authors.lastname: Graham
authors.forename: John
authors.initials: J
authors.lastname: Leaney
authors.forename: John
authors.initials: J
authors.lastname: Grigg
authors.forename: Ivan
authors.initials: I
authors.lastname: Goldberg
authors.forename: Frank
authors.initials: F
authors.lastname: Billson
authors.forename: Alexander
authors.initials: A
authors.lastname: Klistorner
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001369:Axons / Q000473:pathology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D010781:Photography; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012607:Scotoma / Q000175:diagnosis; D041623:Tomography, Optical Coherence; D058609:Visual Field Tests; D014794:Visual Fields