title: Variability of full-field electroretinogram responses in subjects without diffuse photoreceptor cell disease.
abstract: OBJECTIVE
  To evaluate test-retest variability in electroretinogram (ERG) responses in subjects without evidence of diffuse photoreceptor cell disease.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  Forty subjects without diffuse photoreceptor cell disease.
  
  
  METHODS
  Serial ERGs were performed on 40 subjects (mean age at the time of first ERG: 54 years; range: 38-75 years) over a period of 2 to 6 years. These subjects participated in a study by a pharmaceutical company investigating the effects of certain drugs, used for gastrointestinal disorders, on retinal function. None of the subjects showed any evidence of progressive change in retinal function related to the medications. The ERG responses that were evaluated included amplitudes and implicit times for the dark-adapted rod-isolated and rod-dominant responses, light-adapted single flash response, and both light- and dark-adapted 31-Hz flicker responses.
  
  
  METHODS
  The data were analyzed by using analysis of variance methods, and a threshold criteria for significant change with 95% confidence was calculated for implicit times and an increase or decrease in ERG amplitudes.
  
  
  RESULTS
  The threshold for significant change varied depending on the ERG stimulus. For the dark-adapted stimuli, a significant decrease in amplitude varied from 35% to 42% as compared with a variation of 53% to 73% for a significant increase. For the light-adapted stimuli, a significant decrease in amplitude varied by 52% as compared with a variation of 109% to 110% for a significant increase. The threshold for significant change for implicit times varied from 3.0 milliseconds to 8.7 milliseconds.
  
  
  CONCLUSIONS
  The measured test-retest variability in ERG amplitudes and implicit times in subjects without diffuse photoreceptor cell disease underscores the importance of conducting similar comprehensive studies of variability in patients with acquired and hereditary retinal diseases. These data are also of value for monitoring disease progression and in future therapeutic trials.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Eye and Ear Infirmary, University of Illinois at Chicago, 60612, USA.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Grover
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Fishman
authors.forename: David G
authors.initials: DG
authors.lastname: Birch
authors.forename: Kirsten G
authors.initials: KG
authors.lastname: Locke
authors.forename: Bernard
authors.initials: B
authors.lastname: Rosner
mesh_terms: D000328:Adult; D000368:Aged; D016001:Confidence Intervals; D003623:Dark Adaptation; D004596:Electroretinography / Q000592:standards*; D006801:Humans; D008875:Middle Aged; D010775:Photic Stimulation; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D011446:Prospective Studies; D012164:Retinal Diseases / Q000503:physiopathology; D012684:Sensory Thresholds