title: Evaluation of corneal thickness using a Scheimpflug-Placido disk corneal analyzer and comparison with ultrasound pachymetry in eyes after laser in situ keratomileusis.
abstract: OBJECTIVE
  To evaluate the repeatability and reproducibility of corneal thickness measurements in post-laser in situ keratomileusis (LASIK) eyes using a rotating Scheimpflug camera combined with a Placido disk corneal topographer (Sirius) and compare the results with those of ultrasound (US) pachymetry.
  
  
  METHODS
  Eye Hospital of Wenzhou Medical College, Wenzhou, China.
  
  
  METHODS
  Comparative evaluation of a diagnostic test or technology.
  
  
  METHODS
  Patients were examined 3 times with the Scheimpflug-Placido topographer by 2 examiners. The central pupil corneal thickness (CTpupil), apical corneal thickness (CTapex), and thinnest corneal thickness (CTthinnest) were recorded. After noncontact examinations, US pachymetry was used to obtain the central corneal thickness (CCT).
  
  
  RESULTS
  The Scheimpflug-Placido topographer showed high intraoperator repeatability as indicated by a test-retest repeatability of less than 8.5 μm for CTpupil, CTapex, and CTthinnest, The coefficients of variation (CoV) were less than 0.7%, and the intraclass correlation coefficient was higher than 0.99. Excellent results were also obtained for interoperator reproducibility. All CoVs were less than 0.5%. The 95% limits of agreement between the Scheimpflug-Placido measurement and the US pachymetry measurements were narrow (-16.62 to 12.44 μm for CTpupil versus US pachymetry CCT; -17.49 to 12.16 μm for CTapex versus US pachymetry CCT; -18.59 to 10.90 μm for CTthinnest versus US pachymetry CCT).
  
  
  CONCLUSIONS
  The Scheimpflug-Placido topographer showed excellent intraoperator repeatability and interoperator reproducibility of CTpupil, CTapex, and CTthinnest measurements in post-LASIK eyes. The CCT measurements obtained using the device were in high agreement with those obtained by US pachymetry, suggesting that the 2 devices are interchangeable.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical College, and the Key Laboratory of Vision Science, Ministry of Health PR China, Wenzhou, Zhejiang, China.
authors.forename: Jinhai
authors.initials: J
authors.lastname: Huang
authors.forename: Weicong
authors.initials: W
authors.lastname: Lu
authors.forename: Giacomo
authors.initials: G
authors.lastname: Savini
authors.forename: Liang
authors.initials: L
authors.lastname: Hu
authors.forename: Chao
authors.initials: C
authors.lastname: Pan
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Weina
authors.initials: W
authors.lastname: Tan
authors.forename: Jia
authors.initials: J
authors.lastname: Chen
authors.forename: Qinmei
authors.initials: Q
authors.lastname: Wang
mesh_terms: D000328:Adult; D003315:Cornea / Q000473:pathology*; D063171:Corneal Pachymetry / Q000379:methods*; D019781:Corneal Topography / Q000379:methods*; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D009216:Myopia / Q000601:surgery*; D015588:Observer Variation; D009929:Organ Size; D011184:Postoperative Period; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult