title: Intrasubject repeatability of corneal power, thickness, and wavefront aberrations with a new version of a dual rotating Scheimpflug-Placido system.
abstract: OBJECTIVE
  To determine the intrasubject repeatability of a recently introduced dual-camera rotating Scheimpflug-Placido imaging system (Galilei G4) in determining corneal thickness, power, and wavefront aberrations in young healthy subjects.
  
  
  METHODS
  University of Valencia, Valencia, Spain.
  
  
  METHODS
  Prospective evaluation of diagnostic technology.
  
  
  METHODS
  The study comprised right eyes of 25 subjects aged 20 to 40 years with a spherical equivalent ranging from -4.25 to +1.00 diopters. The central corneal thickness, thinnest point value and location, anterior and posterior surface curvatures, total corneal power, and corneal wavefront aberrations were measured for distance vision using the dual Scheimpflug-Placido system. Three consecutive measurements were taken in each eye.
  
  
  RESULTS
  Twenty-five eyes were evaluated. Repeated-measures analysis of variance showed the only statistically significant difference between the 3 repeated measures to be in trefoil aberration. Intraclass correlation coefficients (ICCs) were higher than 0.950 for all the parameters except the thinnest point chord distance to geometric corneal center (0.528) and chord angle (0.742), corneal astigmatism (0.811) and its vector components J0 (0.891) and J45 (0.724), and all wavefront aberrations.
  
  
  CONCLUSIONS
  The new dual Scheimpflug-Placido system had high intraobserver repeatability for corneal power and thickness and moderate repeatability for corneal astigmatism and corneal wavefront aberrations in healthy corneas with low astigmatism. This iteration of the device performed better in young healthy corneas than preceding versions.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Optometry Research Group, Optics Department, University of Valencia, Valencia, Spain. Electronic address: alejandro.cervino@uv.es.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cerviño
authors.affiliation: From the Optometry Research Group, Optics Department, University of Valencia, Valencia, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Dominguez-Vicent
authors.affiliation: From the Optometry Research Group, Optics Department, University of Valencia, Valencia, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Ferrer-Blasco
authors.affiliation: From the Optometry Research Group, Optics Department, University of Valencia, Valencia, Spain.
authors.forename: Santiago
authors.initials: S
authors.lastname: García-Lázaro
authors.affiliation: From the Optometry Research Group, Optics Department, University of Valencia, Valencia, Spain.
authors.forename: Cesar
authors.initials: C
authors.lastname: Albarrán-Diego
mesh_terms: D000328:Adult; D003315:Cornea / Q000033:anatomy & histology* / Q000502:physiology*; D063171:Corneal Pachymetry; D057108:Corneal Wavefront Aberration / Q000503:physiopathology*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D015588:Observer Variation; D010781:Photography / Q000295:instrumentation; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology*; D015203:Reproducibility of Results; D055815:Young Adult