title: Reliability and application variability of a commercially available infrared videonystagmography unit.
abstract: OBJECTIVE
  Nystagmus is a condition of involuntary eye movement. The causes for nystagmus may be congenital, idiopathic, or acquired. Considerable debate exists on the therapeutic potential of various surgical techniques. Currently, there are neither standardized protocols nor devices to record quantitative data on patients with clinical nystagmus undergoing various procedures at multiple centers to facilitate randomized prospective clinical trials.
  
  
  METHODS
  The authors evaluated the reliability and variability of a commercially available infrared videonystagmography unit by recording eye movement waveforms elicited from normal volunteers (n = 117, 13 patients, 9 trials) by different examiners (A, B, and C). Five movement characteristics were examined, including saccadic latency, velocity and precision, and pursuit gain and velocity.
  
  
  RESULTS
  The overall test/retest variability was low, where the median coefficient of variation of the three testers for all five eye movement categories was less than 15%, and less than 10% of the coefficients of variation calculated were more than 20%. However, there was a significant difference in interobserver variability for all outcomes, except saccade latency.
  
  
  CONCLUSIONS
  The between-tester analysis was found to have greater variability than the test/retest reliability analysis. Future studies at multiple sites using videonystagmography measurements should aim to have each patient repeatedly tested by the same tester. In anticipation of multicenter, randomized, prospective clinical trials of surgical procedures for nystagmus, standardized protocols for nystagmographic data collection and analysis must be validated both within and among participating centers.
authors.forename: Amanda
authors.initials: A
authors.lastname: Gerling
authors.forename: Szu-Yun
authors.initials: SY
authors.lastname: Leu
authors.forename: Szu-Yen
authors.initials: SY
authors.lastname: Leu
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Morton
authors.forename: Julio
authors.initials: J
authors.lastname: Echegoyen
authors.forename: Angele
authors.initials: A
authors.lastname: Nalbandian
authors.forename: Robert W
authors.initials: RW
authors.lastname: Lingua
mesh_terms: D000328:Adult; D000368:Aged; D004584:Electronystagmography / Q000592:standards*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007259:Infrared Rays; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012438:Saccades / Q000502:physiology*; D014741:Video Recording