title: Variability in Oculus Pentacam tomographer measurements in patients with keratoconus.
abstract: OBJECTIVE
  The aim of this study was to determine intertest variability of measurements taken by the Pentacam tomographer in eyes with keratoconus.
  
  
  METHODS
  Three Pentacam measurements with 1-minute intervals were taken from 101 eyes (81 keratoconus and 20 controls) from 57 patients (47 keratoconus and 10 controls) by the same examiner and under the same conditions. Keratoconus eyes were divided into 3 subgroups based on topographic astigmatism (TA). Variability in astigmatism, mean keratometry, central corneal thickness, and fixation values were compared within the patient subgroups versus normal controls.
  
  
  RESULTS
  Variability of all studied parameters (astigmatism, mean keratometry, central corneal thickness, and fixation values) increased with increasing TA in patients with keratoconus.
  
  
  CONCLUSIONS
  Pentacam measurements show increased variability in patients with keratoconus. The degree of variability correlates with TA.
authors.affiliation: *Cornea and Anterior Segment Service, Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD; †Department of Ophthalmology, Federal University of São Paulo/Paulista School of Medicine, São Paulo, Brazil; ‡Department of Ophthalmology, State University of Rio de Janeiro, Rio de Janeiro, Brazil; §Dana Center for Preventive Ophthalmology, Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD; ¶Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; ‖Department of Ophthalmology, Wayne State University School of Medicine, Kresge Eye Institute, Detroit, MI; and **Ophthalmology Unit, Medstar Washington Hospital Center, Washington, DC.
authors.forename: Lucas M M
authors.initials: LM
authors.lastname: Vianna
authors.forename: Beatriz
authors.initials: B
authors.lastname: Muñoz
authors.forename: Frank S
authors.initials: FS
authors.lastname: Hwang
authors.forename: Arusha
authors.initials: A
authors.lastname: Gupta
authors.forename: Albert S
authors.initials: AS
authors.lastname: Jun
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000473:pathology; D016022:Case-Control Studies; D003315:Cornea / Q000473:pathology; D019781:Corneal Topography / Q000379:methods*; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D007640:Keratoconus / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D010781:Photography / Q000295:instrumentation*; D014054:Tomography / Q000295:instrumentation*; D055815:Young Adult