title: Corneal thickness measurements: scanning-slit corneal topography and noncontact specular microscopy versus ultrasonic pachymetry.
abstract: OBJECTIVE
  To compare central corneal thickness measurements taken with 3 pachymetry systems: Orbscan scanning-slit corneal topography/pachymetry, Topcon SP2000P noncontact specular microscopy, and Tomey ultrasonic pachymetry.
  
  
  METHODS
  Multicenter study, Tokyo, Japan.
  
  
  METHODS
  In 216 healthy eyes of 114 subjects, scanning-slit topography, noncontact specular microscopy, and ultrasonic pachymetry were used in that sequence to record central corneal thickness. In another 20 healthy eyes of 13 subjects, 2 sets of measurements were repeated for each pachymetry to assess repeatability.
  
  
  RESULTS
  The mean central corneal thickness was compatible between scanning-slit topography (546.9 micrometers +/- 35.4 [SD] ) and ultrasonic pachymetry (548.1 +/- 33.0 micrometers); however, noncontact specular microscopy gave a significantly smaller mean (525.3 +/- 31.4 micrometers) than the other 2 tests (P<.001, Tukey multiple comparison). There were significant linear correlations between scanning-slit topography and noncontact specular microscopy (r = 0.846, P<.001), noncontact specular microscopy and ultrasonic pachymetry (r = 0.897, P<.001), and ultrasonic pachymetry and scanning-slit topography (r = 0.852, P<.001). Noncontact specular microscopy tended to show the best repeatability; however, the difference was not statistically significant (P =.663, repeated-measure analysis of variance).
  
  
  CONCLUSIONS
  Corneal thickness readings were comparable between scanning-slit topography and pachymetry; noncontact specular microscopy gave significantly smaller values. The measurements of the 3 methods showed significant linear correlations with one another. All methods provided acceptable repeatability of measurements.
authors.affiliation: Department of Ophthalmology, University of Tokyo School of Medicine, Tokyo, Japan.
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Suzuki
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Oshika
authors.forename: Kotaro
authors.initials: K
authors.lastname: Oki
authors.forename: Isao
authors.initials: I
authors.lastname: Sakabe
authors.forename: Aiko
authors.initials: A
authors.lastname: Iwase
authors.forename: Shiro
authors.initials: S
authors.lastname: Amano
authors.forename: Makoto
authors.initials: M
authors.lastname: Araie
mesh_terms: D000328:Adult; D000368:Aged; D003315:Cornea / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D019781:Corneal Topography / Q000592:standards; D006801:Humans; D008853:Microscopy / Q000592:standards; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000592:standards