title: Repeatability of whole-cornea measurements using an anterior segment imaging device based on OCT and Placido-disk.
abstract: BACKGROUND
  Current advances in refractive surgery require high accuracy of corneal measurements. We aim to evaluate the repeatability of topographic measurements using an integrated Placido disk - OCT device.
  
  
  METHODS
  Thirty right eyes of thirty healthy and young subjects were included. The topographic parameters of simulated keratometry, asphericity, minimum pachymetry, white-to-white distance, spherical aberration and corneal elevation were studied. Three measurements were taken by the same observer using the Visante omni device. The coefficient of repeatability (CoR), coefficient of variation (CoV) and intraclass correlation coefficient (ICC) were calculated to assess the repeatability. The Bland-Altman graphical method was also applied.
  
  
  RESULTS
  No significant differences between repeated measurements were found. The mean difference for simulated keratometry was between 0.01 and 0.02 D. For asphericity was -0.01 ± 0.02, and for minimum pachymetry, spherical aberration and WTW was equal or less than 0.02 mm. The mean differences for corneal elevation, in millimeters and diopters, were between 0.00 and 0.01. Overall, most topographic parameters had a CoV less than 0.4%, a CoR less than 0.3 and an ICC higher than 0.98.
  
  
  CONCLUSIONS
  The Visante omni device provides good repeatability for topographical measurements of simulated keratometry, asphericity, pachymetry, spherical aberration and corneal elevation.
authors.affiliation: a Optometry Research Group (GIO), Department of Optics and Optometry and Vision Sciences , University of Valencia , Burjassot , Spain.
authors.forename: Noelia
authors.initials: N
authors.lastname: Martínez-Albert
authors.affiliation: a Optometry Research Group (GIO), Department of Optics and Optometry and Vision Sciences , University of Valencia , Burjassot , Spain.
authors.forename: José J
authors.initials: JJ
authors.lastname: Esteve-Taboada
authors.affiliation: a Optometry Research Group (GIO), Department of Optics and Optometry and Vision Sciences , University of Valencia , Burjassot , Spain.
authors.forename: Robert
authors.initials: R
authors.lastname: Montés-Micó
mesh_terms: D000328:Adult; D003315:Cornea / Q000033:anatomy & histology*; D063171:Corneal Pachymetry; D019781:Corneal Topography / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000295:instrumentation* / Q000379:methods*; D055815:Young Adult
keywords: Placido disk; cornea; optical coherence tomography; repeatability; topography