title: Repeatability of corneal thickness measured using an Oculus Pentacam.
abstract: OBJECTIVE
  To evaluate the repeatability of corneal thickness measurements over time, obtained with an Oculus Pentacam.
  
  
  METHODS
  Measurements of corneal thickness (apical and peripheral) were performed at three different sessions in one eye of 23 healthy subjects, using an Oculus Pentacam instrument. In each session, three consecutive measurements were taken (without realignment) by the same observer. Measurements were performed, immediately after a blink.
  
  
  RESULTS
  Mean values obtained were in agreement with published literature values for central corneal thickness (mean +/- SEM: 546.23 +/- 5.24 microm for first session over the first 1 min, 545.13 +/- 5.49 microm for second session 1 h later, and 543.23 +/- 4.96 microm for the third session measured 1 week later). The data showed an increase in corneal thickness towards the periphery with a decrease in intraobserver reproducibility. The confidence limits in the Bland and Altman charts for pachymetry at the corneal apex ranged between -10.91 microm and 13.00 microm within the first session measured over the first 1 min, -13.43 microm to 11.23 microm between the first and second sessions after 1 h and -11.99 microm to 10.02 microm between the first and third sessions after 1 week. The confidence limits were found to increase towards the peripheral cornea. There was no significant difference in within-subjects variance between the three time scales (p > 0.05 for all parameters measured).
  
  
  CONCLUSIONS
  Our data showed that the Oculus Pentacam provides repeatable measures of corneal thickness when measured within a few seconds, after 1 h, and 1 week.
authors.affiliation: Faculty of Life Sciences, The University of Manchester, United Kingdom. marco.miranda@postgrad.manchester.ac.uk
authors.forename: Marco A
authors.initials: MA
authors.lastname: Miranda
authors.forename: Hema
authors.initials: H
authors.lastname: Radhakrishnan
authors.forename: Clare
authors.initials: C
authors.lastname: O'Donnell
mesh_terms: D000328:Adult; D000869:Anterior Eye Segment / Q000033:anatomy & histology*; D003315:Cornea / Q000033:anatomy & histology*; D019781:Corneal Topography / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D013997:Time Factors; D055815:Young Adult