title: Visual evoked potentials elicited by pseudorandom stimulation from patients with macular degeneration.
abstract: OBJECTIVE
  To investigate the effect of a central scotoma on the amplitude, implicit time (IT), and temporal frequency characteristics (TFC) of the visual evoked potentials (VEPs) elicited by a pseudorandom binary sequence (PRBS) stimulus in age-related macular degeneration (AMD) patients.
  
  
  METHODS
  Twenty-six patients with AMD, 17 eyes with visual acuity of less than 20/100, and 9 eyes with visual acuity between 20/70 and 20/25, were examined. Nine eyes of age-matched healthy volunteers served as controls. To elicit the PRBS-VEPs, one eye was stimulated with a PRBS stimulus. The first-order kernel was calculated from a cross-correlation between the PRBS and the VEPs. The Fourier transformed first-order kernel was used as the TFC of the visual system.
  
  
  RESULTS
  The mean IT of P2 (second positive peak) of the first-order kernel was significantly delayed (t-test, P <.05), and the P2-N2 (peak-to-peak of P2 and second negative peak N2) amplitude was significantly reduced (t-test, P <.01) in eyes with AMD. A depression of the TFC values in the 6-18 Hz band was prominent in patients with AMD (t-test, P <.01).
  
  
  CONCLUSIONS
  PRBS-VEPs demonstrated a prolonged IT and reduced amplitude of the first-order kernel, and reduced TFC with a reduction of visual acuity in patients with macular degeneration.
authors.affiliation: Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, Graduate School, Tokyo, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Nemoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mori
authors.forename: Motohiro
authors.initials: M
authors.lastname: Kiyosawa
authors.forename: Wei Fang
authors.initials: WF
authors.lastname: Wang
authors.forename: Manabu
authors.initials: M
authors.lastname: Mochizuki
authors.forename: Keiko
authors.initials: K
authors.lastname: Momose
mesh_terms: D000368:Aged; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D008268:Macular Degeneration / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012160:Retina / Q000503:physiopathology*; D012607:Scotoma / Q000503:physiopathology*; D013997:Time Factors