title: Comparison of high-resolution Scheimpflug and high-frequency ultrasound biomicroscopy to anterior-segment OCT corneal thickness measurements.
abstract: BACKGROUND
  The purpose of this study was to compare and correlate central corneal thickness in healthy, nonoperated eyes with three advanced anterior-segment imaging systems: a high-resolution Scheimpflug tomography camera (Oculyzer II), a spectral-domain anterior-segment optical coherence tomography (AS-OCT) system, and a high-frequency ultrasound biomicroscopy (HF-UBM) system.
  
  
  METHODS
  Fifty eyes randomly selected from 50 patients were included in the study. Inclusion criteria were healthy, nonoperated eyes examined consecutively by the same examiner. Corneal imaging was performed by three different methods, ie, Oculyzer II, spectral-domain AS-OCT, and FH-UBM. Central corneal thickness measurements were compared using scatter diagrams, Bland-Altman plots (with bias and 95% confidence intervals), and two-paired analysis.
  
  
  RESULTS
  The coefficient of determination (r (2)) between the Oculyzer II and AS-OCT measurements was 0.895. Likewise, the coefficient was 0.893 between the Oculyzer II and HF-UBM and 0.830 between the AS-OCT and HF-UBM. The trend line coefficients of linearity were 0.925 between the Oculyzer II and the AS-OCT, 1.006 between the Oculyzer II and HF-UBM, and 0.841 between the AS-OCT and HF-UBM. The differences in average corneal thickness between the three pairs of CCT measurements were -6.86 μm between the Oculyzer II and HF-UBM, -12.20 μm between the AS-OCT and Oculyzer II, and +19.06 μm between the HF-UBM and AS-OCT.
  
  
  CONCLUSIONS
  The three methods used for corneal thickness measurement are highly correlated. Compared with the Scheimplug and ultrasound devices, the AS-OCT appears to report a more accurate, but overally thinner corneal pachymetry.
authors.affiliation: Laservision.gr Eye Institute, Athens, Greece ; New York University Medical School, New York, NY, USA.
authors.forename: Anastasios John
authors.initials: AJ
authors.lastname: Kanellopoulos
authors.affiliation: Laservision.gr Eye Institute, Athens, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Asimellis
keywords: anterior eye segment; corneal thickness; high-frequency ultrasound biomicroscopy; high-resolution Pentacam; optical coherence tomography