title: Repeatability and reproducibility of the BVI ultrasonic Pachymeter.
abstract: OBJECTIVE
  To evaluate the interobserver and intraobserver reliability of a commercially available, portable, ultrasonic pachymeter.
  
  
  METHODS
  For the interobserver variability study, 42 healthy subjects underwent repeated ultrasonic pachymetry under topical anaesthesia performed by two observers. For the intraobserver study, another 30 further healthy subjects underwent repeated pachymetry by one of the observers. Agreement was analysed by means of Bland-Altman plots and by determination of the intraclass correlation coefficient.
  
  
  RESULTS
  For the interobserver variability study, the mean measurement difference between observers was 0.7 microm (95% CI -0.8-2.2 microm) and the intraclass correlation coefficient was 0.9958 (95% CI 0.9922-0.9977). The Bland-Altman plot showed narrow limits of agreement with respect to central corneal thickness (CCT). For the intraobserver variability study, the mean difference between the repeated measurements was 0.9 microm (95% CI -3.1-1.3 microm). The intraclass correlation coefficient was 0.9934 (95% CI 0.9863-0.9969). A Bland-Altman plot again showed narrow limits of agreement with respect to CCT. The mean CCT for 72 subjects was 538 microm (95% CI 528-545 microm).
  
  
  CONCLUSIONS
  Measurements of CCT using the BVI Pocket Pachymeter were repeatable and had excellent interobserver reliability. Measurement variation amounted to less than 0.2% assuming a mean CCT of 538 microm.
authors.affiliation: Department of Optometry and Ophthalmic Dispensing Anglia Polytechnic University Cambridge, UK. contact@pinakin-gunvant.com
authors.forename: P
authors.initials: P
authors.lastname: Gunvant
authors.forename: D C
authors.initials: DC
authors.lastname: Broadway
authors.forename: R J
authors.initials: RJ
authors.lastname: Watkins
mesh_terms: D000328:Adult; D003315:Cornea / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D014463:Ultrasonography