title: Central corneal thickness measured by the Orbscan II system, contact ultrasound pachymetry, and the Artemis 2 system.
abstract: OBJECTIVE
  To compare central corneal thickness (CCT) measurements by the Orbscan II device, contact ultrasound (US) pachymetry, and the noncontact Artemis 2 scanning US system.
  
  
  METHODS
  Department of Ophthalmology, Weill Cornell Medical College, New York, New York, USA.
  
  
  METHODS
  The CCT in 40 eyes (20 normal subjects) was measured by the Orbscan II followed by contact US pachymetry and then the Artemis 2. Results were compared using analysis of variance (ANOVA), paired t tests, and Bland-Altman plots.
  
  
  RESULTS
  There was a significant difference in CCT measurements between the 3 modes (F = 32.84, P = .0001, 1-way ANOVA). Artemis 2 and US pachymetry measurements were highly correlated (r2 = 0.963, P < .0001), although Artemis 2 values were a mean of 11.2 microm +/- 6.6 (SD) thinner than pachymetry values. Artemis 2 and Orbscan II measurements were less well correlated (r2 = 0.851, P < .001); Orbscan II values were a mean of 7.5 +/- 15.7 microm thinner than Artemis 2 values. Orbscan II values showed a trend toward increasing underestimation of CCT in thinner corneas.
  
  
  CONCLUSIONS
  Ultrasound pachymetry and Artemis 2 CCT measurements were highly correlated; the 11 microm mean difference in measurements may be attributed to decentration, oblique incidence of the probe to the cornea, or possibly the effect of topical anesthesia with contact pachymetry. Although the mean difference between Orbscan II and Artemis 2 values was 7.5 microm, Orbscan values were less correlated than Artemis 2 values with contact US pachymetry and were prone to underestimation of the CCT in thinner corneas.
authors.affiliation: Department of Ophthalmology, Weill Cornell Medical College, New York Presbyterian Hospital, New York, New York 10065, USA.
authors.forename: Tania
authors.initials: T
authors.lastname: Paul
authors.forename: Mira
authors.initials: M
authors.lastname: Lim
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Starr
authors.forename: Harriet O
authors.initials: HO
authors.lastname: Lloyd
authors.forename: D Jackson
authors.initials: DJ
authors.lastname: Coleman
authors.forename: Ronald H
authors.initials: RH
authors.lastname: Silverman
mesh_terms: D000328:Adult; D001837:Body Weights and Measures; D003315:Cornea / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D019781:Corneal Topography; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D014463:Ultrasonography