title: Detecting early to mild glaucomatous damage: a comparison of the multifocal VEP and automated perimetry.
abstract: OBJECTIVE
  To gain better understanding of the relationship between abnormalities detected by the multifocal VEP (mfVEP) compared with those detected by static achromatic, automated perimetry in patients with glaucoma.
  
  
  METHODS
  Fifty patients were studied who had open-angle glaucoma that met the following criteria: (1) a mean deviation (MD) of better than -8 dB in both eyes on the 24-2 Humphrey visual field (HVF) test (Carl Zeiss Meditec, Dublin, CA); and (2) glaucomatous damage in at least one eye, as defined by a glaucomatous optic disc and an abnormal 24-2 HVF test result (pattern standard deviation [PSD] <5% and/or glaucoma hemifield test [GHT] results outside normal limits). Monocular mfVEPs were obtained from each eye by using a pattern-reversal dartboard array, 44.5 degrees in diameter, which contained 60 sectors. Recording electrodes were placed at the inion (I) and I+4 cm, and also at two lateral locations up 1 cm and over 4 cm from I. Monocular and interocular mfVEP probability plots were derived by comparing the results with those of normal control subjects. For both the HVF and mfVEP probability plots, a hemifield was classified as abnormal if three or more contiguous points were significant at less than 5%, with at least one at less than 1%.
  
  
  RESULTS
  Of the 200 hemifields tested (50 patients x two eyes x two hemifields), 75 showed significant clusters on the HVF, and 74 (monocular probability plot) and 93 (monocular or interocular plot) showed significant clusters on the mfVEP. Overall, the HVF and mfVEP results agreed on 74% of the hemifields, and 90 hemifields were normal and 58 were abnormal on both the mfVEP (interocular and/or monocular abnormal) and HVF cluster tests. Of the 52 disagreements, 35 hemifields had a significant cluster on the mfVEP, but not on the HVF, whereas the reverse was true of 17 hemifields. A case-by-case analysis indicated that misses and false-positive results occurred on both the HVF and mfVEP tests.
  
  
  CONCLUSIONS
  As predicted from a theoretical analysis, under these conditions (i.e., the signal-to-noise level) the HVF and monocular mfVEP tests showed a comparable number of defects, and, with the addition of the interocular test, the mfVEP showed more abnormalities than the HVF. However, although there were abnormalities detected by the mfVEP that were missed by the HVF, the reverse was true as well.
authors.affiliation: Department of Psychology, Columbia University, New York, New York 10027, USA. dch3@columbia.edu
authors.forename: Donald C
authors.initials: DC
authors.lastname: Hood
authors.forename: Phamornsak
authors.initials: P
authors.lastname: Thienprasiddhi
authors.forename: Vivienne C
authors.initials: VC
authors.lastname: Greenstein
authors.forename: Bryan J
authors.initials: BJ
authors.lastname: Winn
authors.forename: Nitin
authors.initials: N
authors.lastname: Ohri
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Liebmann
authors.forename: Robert
authors.initials: R
authors.lastname: Ritch
mesh_terms: D000328:Adult; D000368:Aged; D005074:Evoked Potentials, Visual; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008875:Middle Aged; D009898:Optic Disk / Q000473:pathology; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D011336:Probability; D014786:Vision Disorders / Q000175:diagnosis*; D058609:Visual Field Tests / Q000379:methods*; D014794:Visual Fields