title: Comparison and repeatability of keratometric and corneal power measurements obtained by Orbscan II, Pentacam, and Galilei corneal tomography systems.
abstract: OBJECTIVE
  To assess the repeatability and comparability of corneal power and central corneal thickness (CCT) measurements obtained using Orbscan II (Bausch & Lomb), Pentacam (Oculus), and Galilei (Ziemer) tomographers.
  
  
  METHODS
  Prospective, comparative study.
  
  
  METHODS
  setting: Departments of Ophthalmology, University of Auckland and Auckland District Health Board, Auckland, New Zealand. study population: Thirty eyes of 30 healthy participants. observations. CCT and corneal power measured using Orbscan II, Pentacam, and Galilei tomography. main outcome measures: Degree of agreement in and repeatability of CCT and corneal power measures.
  
  
  RESULTS
  Orbscan II measured significantly lower CCT compared with Pentacam (20 μm; P < .0005) and Galilei (18 μm; P < .0005). The Orbscan II had wide limits of agreement when compared with both the Galilei (-11 to 47 μm) and Pentacam (-88 to 47 μm). For each device, the intraclass correlation coefficient for CCT was higher than 0.9. The coefficient of variation ranged from 0.33% to 0.93%. There was no significant difference in mean steep keratometry or mean flat keratometry between instrument pairs. However, there was poor agreement in flat keratometry and steep keratometry obtained by Orbscan II compared with those obtained by the Galilei and Pentacam.
  
  
  CONCLUSIONS
  The keratometry and pachymetry measurements obtained by Orbscan II, Pentcam, and Galilei tomographers were sufficiently disparate that the 3 devices could not be considered equivalent. All 3 devices demonstrated a high level of repeatability, although the Galilei exhibited the best repeatability.
authors.affiliation: Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
authors.forename: Alexandra Z
authors.initials: AZ
authors.lastname: Crawford
authors.forename: Dipika V
authors.initials: DV
authors.lastname: Patel
authors.forename: Charles N J
authors.initials: CN
authors.lastname: McGhee
mesh_terms: D000328:Adult; D003315:Cornea / Q000033:anatomy & histology* / Q000502:physiology*; D063171:Corneal Pachymetry / Q000295:instrumentation*; D019781:Corneal Topography / Q000295:instrumentation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010781:Photography / Q000295:instrumentation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult