title: A multicenter comparison study of the Humphrey Field Analyzer I and the Humphrey Field Analyzer II.
abstract: OBJECTIVE
  The purpose of the study is to determine the comparability of the 30-2 full-threshold program in the original Humphrey Field Analyzer (HFA) I to the same test procedure in the new Humphrey Field Analyzer II.
  
  
  METHODS
  At each of five clinical centers, one eye of patients with ocular hypertension and normal visual fields, patients with early glaucomatous visual field loss, and patients with more advanced visual field loss were tested with the two instruments plus a retest on a separate HFA I. All participants had undergone at least one prior visual field examination. To minimize the influence of any residual learning or fatigue effects, the order of testing for the three visual field examinations was counterbalanced across subjects. A total of 250 patients were tested (81 patients with ocular hypertension, 81 patients with early glaucomatous visual field loss, and 88 patients with more advanced glaucomatous visual field loss).
  
  
  RESULTS
  No statistically significant differences were observed between thresholds, visual field indices, or reliability indices obtained with the HFA I and the HFA II. The small differences between the two instruments were equivalent to the variation observed for test-retest measures using only the HFA I. These results were consistent across the range of visual field characteristics shown by the ocular hypertensive, early glaucoma, and moderate glaucoma patient groups.
  
  
  CONCLUSIONS
  The authors' results indicate that there are no differences in the visual field results obtained with the HFA I and the HFA II. These findings suggest that with careful attention to test protocols, the HFA I and HFA II may be used interchangeably to observe patients, even within the context of multicenter clinical trials.
authors.affiliation: Department of Ophthalmology, University of California, Davis, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Johnson
authors.forename: G A
authors.initials: GA
authors.lastname: Cioffi
authors.forename: S M
authors.initials: SM
authors.lastname: Drance
authors.forename: D
authors.initials: D
authors.lastname: Gaasterland
authors.forename: R P
authors.initials: RP
authors.lastname: Mills
authors.forename: F
authors.initials: F
authors.lastname: Ashburn
authors.forename: P
authors.initials: P
authors.lastname: Hnik
authors.forename: R E
authors.initials: RE
authors.lastname: Van Coevorden
mesh_terms: D005188:False Negative Reactions; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D009798:Ocular Hypertension / Q000503:physiopathology*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D058609:Visual Field Tests / Q000295:instrumentation / Q000379:methods*; D014794:Visual Fields / Q000502:physiology*