title: Reliability of the corneal thickness measurements with the Pentacam HR imaging system and ultrasound pachymetry.
abstract: OBJECTIVE
  To obtain the central corneal thickness (CCT) of healthy eyes using the rotating Scheimpflug imaging system and compare these results with conventional ultrasound pachymetry values. Interoperator reliability and repeatability of the different techniques were also determined.
  
  
  METHODS
  CCT was measured on the right eye of 46 healthy subjects with the Pentacam HR (Pentacam High Resolution; Oculus, Wetzlar, Germany) and contact ultrasound pachymetry (AL-2000; Tomey, Tennenlohe, Germany) by 2 independent investigators.
  
  
  RESULTS
  Both observers obtained significantly higher CCT readings with the Pentacam HR imaging system (572 ± 33 and 575 ± 31 μm) than with the ultrasound device (546 ± 27 and 548 ± 28 μm) (P < 0.0001, paired Student t test). Strong and significant correlation was found between the 2 pachymetry techniques regardless of the investigator (r = 0.845 and 0.831, Spearman correlation coefficient) (P < 0.0001). For the Pentacam HR values, statistically significant difference was detected between the observers (P = 0.033). For both pachymetry methods, the degree of agreement between the investigators was reflected by the high interoperator intraclass correlation coefficient value (ICC = 0.96). No significant difference was disclosed between the 3 consecutive readings of either instrument (P > 0.05, analysis of variance).
  
  
  CONCLUSIONS
  Significant difference in CCT values between the high-resolution Pentacam imaging system and the ultrasound pachymeter suggests that the 2 techniques cannot be used interchangeably in clinical practice.
authors.affiliation: Department of Ophthalmology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary. lmodis@dragon.klte.hu
authors.forename: László
authors.initials: L
authors.lastname: Módis
authors.forename: Eszter
authors.initials: E
authors.lastname: Szalai
authors.forename: Gábor
authors.initials: G
authors.lastname: Németh
authors.forename: András
authors.initials: A
authors.lastname: Berta
mesh_terms: D000886:Anthropometry; D003315:Cornea / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010781:Photography / Q000295:instrumentation; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000295:instrumentation