title: Voluntary suppression of the multifocal electroretinogram.
abstract: OBJECTIVE
  To describe multifocal electroretinogram (mfERG) responses in 2 patients with nonorganic visual loss and in 11 eyes of 6 healthy persons who suppressed their mfERG responses.
  
  
  METHODS
  Observational case series.
  
  
  METHODS
  The mfERG results were recorded in all individuals using the Veris Science 4.2 instrument. All subjects were instructed to adjust the hexagonal test pattern so that it was in best focus. A second mfERG was recorded subsequently in volunteers who attempted suppression with inattention and poor fixation and by adjusting the focus to greatest blur.
  
  
  METHODS
  Amplitude and latency of mfERG responses.
  
  
  RESULTS
  Suppressed mfERGs in patients with nonorganic visual loss and healthy volunteers demonstrated reduced amplitude, especially centrally. Amplitude reduction was statistically significant in the postsuppression as compared with the presuppression recordings in wave forms N1 and N2. Statistically significant shortening of postsuppression implicit times of P1 and N2 waveforms also was demonstrated.
  
  
  CONCLUSIONS
  The mfERG responses may be suppressed voluntarily. Amplitude may be reduced. In contrast to most reported pathologic conditions, the implicit time is shortened.
authors.affiliation: Wills Eye Hospital, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
authors.forename: Tamara R
authors.initials: TR
authors.lastname: Vrabec
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Affel
authors.forename: John P
authors.initials: JP
authors.lastname: Gaughan
authors.forename: Rod
authors.initials: R
authors.lastname: Foroozan
authors.forename: Matthew T S
authors.initials: MT
authors.lastname: Tennant
authors.forename: James M
authors.initials: JM
authors.lastname: Klancnik
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Jordan
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Savino
mesh_terms: D000328:Adult; D004596:Electroretinography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009433:Neural Inhibition / Q000502:physiology*; D012160:Retina / Q000502:physiology*; D014786:Vision Disorders / Q000503:physiopathology*