title: Pattern reversal ERG and VEP--comparison of stimulation by LED, monitor and a Maxwellian-view system.
abstract: OBJECTIVE
  Pattern stimulation is widely used to detect inner retinal dysfunction. In this work we describe a pattern stimulation technique with LEDs and compare the results with conventional methods.
  
  
  METHODS
  PERG and VEP were derived from three normal subjects. Three different techniques were used to generate a checkerboard pattern reversal stimulus: a 70 Hz monitor, a Maxwellian-view system equipped with a Xenon-arc lamp and a mechanical mirror system, and a LED array (Roland Consult) consisting of 100 white LEDs. Two kinds of luminance (125 and 340 cd/m2) and four temporal frequencies (4, 8, 12 and 24 reversals per second) were studied on three healthy subjects. Additionally, a luminance tuning experiment (30, 60, 90, 125 and 340 cd/m2) was performed on one subject.
  
  
  RESULTS
  Comparison of different stimulation techniques shows reproducible responses of PERG and VEP with all three methods. The LED array leads to slightly smaller amplitudes than both other techniques, which we ascribe to the design of the LED field. No difference of peak times or phases was noticed between different stimulation techniques. A luminance dependency of PERG and VEP is noticeable using stimulation with LED: with decreasing luminance we measured increasing peak times of PERG and VEP and decreasing amplitude of PERG.
  
  
  CONCLUSIONS
  We conclude that central retinal stimulation with checkerboard pattern reversal is possible with LED. It gives comparable results to monitor and Maxwellian-view system.
authors.affiliation: Department of Ophthalmology, Biometry and Epidemiology, University of Erlangen-Nürnberg, Erlangen, Germany. barbara.link@augen.imed.uni-erlangen.de
authors.forename: Barbara
authors.initials: B
authors.lastname: Link
authors.forename: Sylvia
authors.initials: S
authors.lastname: Rühl
authors.forename: Andrea
authors.initials: A
authors.lastname: Peters
authors.forename: Anselm
authors.initials: A
authors.lastname: Jünemann
authors.forename: Folkert K
authors.initials: FK
authors.lastname: Horn
mesh_terms: D000328:Adult; D004596:Electroretinography / Q000379:methods; D004867:Equipment Design; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D010775:Photic Stimulation / Q000295:instrumentation; D012016:Reference Values; D015203:Reproducibility of Results; D012160:Retina / Q000502:physiology*