title: Central and peripheral corneal thickness measured with optical coherence tomography, Scheimpflug imaging, and ultrasound pachymetry in normal, keratoconus-suspect, and post-laser in situ keratomileusis eyes.
abstract: OBJECTIVE
  To compare central (CCT) and peripheral corneal thickness (PCT) using Scheimpflug imaging (Pentacam), high-speed optical coherence tomography (Visante OCT), and ultrasound (US) pachymetry (Sonogage Corneo-Gage Plus) in normal, keratoconus-suspect, and post-laser in situ keratomileusis (LASIK) eyes.
  
  
  METHODS
  Department of Refractive Surgery, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA.
  
  
  METHODS
  The CCT and PCT were retrospectively measured using US pachymetry, Scheimpflug imaging, and high-speed OCT from January 2006 to March 2008. The influence of age and absolute magnitude of corneal thickness were also analyzed. Analysis was by multivariate generalized estimating equations, multivariate linear regression, and linear regression plots.
  
  
  RESULTS
  One hundred sixty-three eyes were analyzed. Ultrasound pachymetry CCT measurements were consistently higher than Scheimpflug and OCT measurements (mean difference 6.5 microm +/- 1.8 [SD] and 7.5 +/- 1.4 microm, respectively) (both P<.0005) in normal eyes; the difference was statistically similar and not greater with keratoconus suspicion, age, or absolute magnitude of corneal thickness (P>.05). Scheimpflug measurements were significantly lower than US pachymetry in post-LASIK eyes (P<.0005). There was no statistically significant difference (mean 0.9 +/- 1.4 microm) in Scheimpflug and OCT CCT measurements (P>.5), although Scheimpflug measurements were significantly lower in post-LASIK eyes (P<.0005). Scheimpflug PCT measurements were higher than OCT measurements, showing more agreement with increasing age (P = .017).
  
  
  CONCLUSIONS
  Scheimpflug and OCT CCT measurements were reproducible but always thinner than US pachymetry in normal and keratoconus-suspect eyes. In post-LASIK eyes, OCT pachymetry maps were more accurate than Scheimpflug maps. The influence of age on PCT requires further study.
authors.affiliation: TEC de Monterrey, School of Medicine, Monterrey, Mexico. yaya_m2p@hotmail.com
authors.forename: Claudia Maria
authors.initials: CM
authors.lastname: Prospero Ponce
authors.forename: Karolinne Maia
authors.initials: KM
authors.lastname: Rocha
authors.forename: Scott D
authors.initials: SD
authors.lastname: Smith
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Krueger
mesh_terms: D000328:Adult; D000368:Aged; D001837:Body Weights and Measures; D003315:Cornea / Q000033:anatomy & histology* / Q000473:pathology* / Q000601:surgery; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000473:pathology*; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D010781:Photography; D015203:Reproducibility of Results; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence; D014463:Ultrasonography; D055815:Young Adult