title: Objective perimetry using a four-channel multifocal VEP system: correlation with conventional perimetry and thickness of the retinal nerve fibre layer.
abstract: OBJECTIVE
  There is evidence that multifocal visual evoked potentials (VEPs) can be used as an objective tool to detect visual field loss. The aim of this study was to correlate multifocal VEP amplitudes with standard perimetry data and retinal nerve fibre layer (RNFL) thickness.
  
  
  METHODS
  Multifocal VEP recordings were performed with a four-channel electrode array using 58 stimulus fields (pattern reversal dartboard). For each field, the recording from the channel with maximal signal-to-noise ratio (SNR) was retained, resulting in an SNR optimised virtual recording. Correlation with RNFL thickness, measured with spectral domain optical coherence tomography and with standard perimetry, was performed for nerve fibre bundle related areas.
  
  
  RESULTS
  The mean amplitudes in nerve fibre related areas were smaller in glaucoma patients than in normal subjects. The differences between both groups were most significant in mid-peripheral areas. Amplitudes in these areas were significantly correlated with corresponding RNFL thickness (Spearman R=0.76) and with standard perimetry (R=0.71).
  
  
  CONCLUSIONS
  The multifocal VEP amplitude was correlated with perimetric visual field data and the RNFL thickness of the corresponding regions. This method of SNR optimisation is useful for extracting data from recordings and may be appropriate for objective assessment of visual function at different locations.
  
  
  BACKGROUND
  This study has been registered at http://www.clinicaltrials.gov (NCT00494923).
authors: Department of Ophthalmology and University Eye Hospital, Friedrich-Alexander University of Erlangen-Nürnberg, Schwabachanlage 6, 91054 Erlangen, Germany. folkert.horn@uk-erlangen.de
authors: Folkert K
authors: FK
authors: Horn
authors: Christoph
authors: C
authors: Kaltwasser
authors: Anselm G
authors: AG
authors: Jünemann
authors: Jan
authors: J
authors: Kremers
authors: Ralf P
authors: RP
authors: Tornow
mesh_terms: D000328:Adult; D004867:Equipment Design; D005074:Evoked Potentials, Visual; D005260:Female; D005902:Glaucoma, Open-Angle; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012607:Scotoma / Q000473:pathology / Q000503:physiopathology*; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence / Q000379:methods*; D058609:Visual Field Tests / Q000295:instrumentation*; D014794:Visual Fields / Q000502:physiology*