title: Pachymetric mapping with Fourier-domain optical coherence tomography.
abstract: OBJECTIVE
  To evaluate the repeatability of Fourier-domain optical coherence tomography (OCT) pachymetric mapping and compare central corneal thickness (CCT) measurements by OCT, ultrasound pachymetry, and scanning-slit tomography.
  
  
  METHODS
  Doheny Eye Institute, University of Southern California, Los Angeles, California, USA.
  
  
  METHODS
  A Fourier-domain OCT system was used to map the corneal thickness in normal eyes with scans centered on the corneal vertex or the pupil. Repeatability of central and pericentral map sectors was assessed by pooled standard deviation. The CCT measurements were compared between the OCT, ultrasound, and scanning-slit devices.
  
  
  RESULTS
  Pupil centration (SD: 1.3 microm central, 1.8 to 3.8 microm pericentral) provided better repeatability than vertex centration (SD: 1.7 microm central, 2.4 to 5.7 microm pericentral) in all sectors (P<.035). The mean CCT was 536.9 microm +/- 27.0 (SD) by OCT, 556.6 +/- 30.5 microm by ultrasound, and 537.2 +/- 32.6 microm by scanning-slit tomography (acoustic factor 0.92). The CCT measured by OCT was significantly thinner than by ultrasound pachymetry (P = .007; mean difference -19.7 microm; 95% limits of agreement [LoA], -40.4 to 0.9 microm) but not than by scanning-slit tomography (P = .2637; mean difference -0.3 microm; 95% LoA, -24.0 to 23.5 microm). The CCT by OCT correlated well with ultrasound and scanning-slit CCTs (r = 0.940 and r = 0.934, respectively).
  
  
  CONCLUSIONS
  Pachymetric mapping with Fourier-domain OCT was highly repeatable. Repeatability was better with pupil-centered scans than with corneal vertex-centered scans. Ultrasound pachymetry, Fourier-domain OCT, and scanning-slit tomography should not be used interchangeably for CCT assessment.
authors.affiliation: Center for Ophthalmic Optics and Lasers, Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Maolong
authors.initials: M
authors.lastname: Tang
authors.forename: Xinbo
authors.initials: X
authors.lastname: Zhang
authors.forename: Camila H
authors.initials: CH
authors.lastname: Salaroli
authors.forename: Jose L
authors.initials: JL
authors.lastname: Ramos
authors.forename: David
authors.initials: D
authors.lastname: Huang
mesh_terms: D000328:Adult; D000886:Anthropometry; D003315:Cornea / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D019781:Corneal Topography; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D033401:Microscopy, Acoustic; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
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