title: Long- and short-term variability of automated perimetry results in patients with optic neuritis and healthy subjects.
abstract: OBJECTIVE
  To measure the short- and long-term variability of automated perimetry in patients with optic neuritis and normal subjects.
  
  
  METHODS
  Prospective case-control design of patients with recovered optic neuritis with intraday and interday repetitions to obtain robust variability measurements. Entry criteria included a corrected pattern SD that was worse than the normal 5% probability level and a mean deviation worse than -3 dB but better than -20 dB. Five Humphrey 30-2 full threshold tests were administered during a 7-hour period (1 test every 2 hours) on the same day and at the same periods on 5 separate days.
  
  
  METHODS
  Seventeen patients with recovered optic neuritis and 10 healthy subjects of similar age.
  
  
  METHODS
  Short-term variability and long-term variability for global visual field data.
  
  
  RESULTS
  Patients with optic neuritis demonstrated variations in visual field sensitivity that were outside the entire range of variability for normal controls. These variations occurred for multiple tests performed on the same day at specific times and for tests performed at specific times on different days. There were no consistent patterns of sensitivity changes that could be attributed to time of day. The most dramatic fluctuations occurred in a patient whose visual fields varied from normal to a hemianopic defect from one week to another and from a partial quadrant loss to a hemianopic defect at different times on the same day. Seven of the patients with optic neuritis also demonstrated intermittent vertical step defects.
  
  
  CONCLUSIONS
  Patients with resolved optic neuritis can have large variations in visual field results on different days and at different times on the same day. The variations affect both the severity and the pattern of visual field loss and do not appear to be consistent across patients. These data indicate that care must be taken when automated visual field results in patients with optic neuritis are interpreted. Distinguishing systematic changes in sensitivity from variability requires more than a comparison of the current visual field with the most recent previous visual field.
authors.affiliation: Department of Neurology, Veterans Affairs Hospital and University of Iowa College of Medicine, Iowa City 52242-1053, USA. michael-wall@uiowa.edu
authors.forename: M
authors.initials: M
authors.lastname: Wall
authors.forename: C A
authors.initials: CA
authors.lastname: Johnson
authors.forename: K E
authors.initials: KE
authors.lastname: Kutzko
authors.forename: R
authors.initials: R
authors.lastname: Nguyen
authors.forename: C
authors.initials: C
authors.lastname: Brito
authors.forename: J L
authors.initials: JL
authors.lastname: Keltner
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D006801:Humans; D008875:Middle Aged; D009902:Optic Neuritis / Q000503:physiopathology*; D011336:Probability; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D058609:Visual Field Tests / Q000379:methods*; D014794:Visual Fields / Q000502:physiology*