title: Validity and repeatability of anterior chamber depth measurements with Pentacam and Orbscan.
abstract: OBJECTIVE
  The purpose of this study was to determine the validity and repeatability of anterior chamber depth (ACD) measurements obtained with a novel rotating Scheimpflug camera (Pentacam; Oculus Optikgeräte GmbH, Wetzlar, Germany) to scanning slit topography (Orbscan; Bausch & Lomb, Rochester, NY).
  
  
  METHODS
  ACD in 60 healthy eyes was measured twice by two independent observers with each modality in random order. A total of eight measurements was performed on each eye. The mean differences between measurements, between observers, and between modalities were calculated, and 95% limits of agreement (LoA) were given as mean +/- 1.96 * standard deviation (SD) of the mean.
  
  
  RESULTS
  The mean ACD values as determined with the different modalities (+/- SD) were 3.18 +/- 0.38 mm for Pentacam imaging and 3.23 +/- 0.40 for Orbscan. The mean difference between the two modalities was 0.047 mm (LoA: 0.176 to -0.081 mm). Within each modality, the limits of agreement of the differences between individual measurements and between different observers were within 0.073 mm or 4% of total ACD. The total variance in the observed data was 0.145. The variance resulting from interindividual differences in ACD was 85%, as a result of the two different modalities 15%, as a result of different observers 0.007%, and as a result of different measurements 0.007%.
  
  
  CONCLUSIONS
  In the assessment of normal eyes, the differences of ACD values measured with Orbscan and Pentacam were within clinically acceptable levels, and inter- and intraobserver variability was considerably below clinically significant levels. Thus, these two modalities can be regarded as interchangeable.
authors.affiliation: Department of Ophthalmology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria. birgit.lackner@meduniwien.ac.at
authors.forename: Birgit
authors.initials: B
authors.lastname: Lackner
authors.forename: Gerald
authors.initials: G
authors.lastname: Schmidinger
authors.forename: Christian
authors.initials: C
authors.lastname: Skorpik
mesh_terms: D000328:Adult; D000867:Anterior Chamber / Q000033:anatomy & histology*; D001837:Body Weights and Measures; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D010781:Photography / Q000295:instrumentation; D015203:Reproducibility of Results