title: Repeatability of intraoperative central corneal and residual stromal thickness measurement using a handheld ultrasound pachymeter.
abstract: OBJECTIVE
  To determine and compare the repeatability of intraoperative central corneal thickness (CCT) and residual stromal bed thickness measurements using a handheld ultrasound (US) pachymeter.
  
  
  METHODS
  London Vision Clinic, London, United Kingdom.
  
  
  METHODS
  Comparative evaluation of a diagnostic test or technology.
  
  
  METHODS
  This study comprised eyes that had laser in situ keratomileusis retreatment by flap lift in which handheld US pachymetry (Corneo-Gage Plus 50 MHz) had been performed intraoperatively. In each case, 5 consecutive measurements were obtained centrally immediately before and after the flap was lifted. The within-eye repeatability was calculated as the standard deviation of the 5 repeated measurements for the CCT measurements and the central residual stromal thickness (RST) measurements.
  
  
  RESULTS
  The study evaluated 134 eyes (79 patients). The mean CCT was 467 μm ± 40 (SD) (range 393 to 577 μm). The repeatability of CCT measurements was 6.83 μm, the coefficient of repeatability was 13.40 μm, and the coefficient of variation (CoV) was 1.46%. The mean central RST was 335 ± 46 μm (range 259 to 465 μm). The repeatability of central RST measurements was 4.91 μm, the coefficient of repeatability was 9.62 μm, and the CoV was 1.46%.
  
  
  CONCLUSIONS
  The repeatability of intraoperative handheld US pachymetry was similar between measurements of CCT and measurements of central RST; the CoV was 1.46% in both cases.
authors: London Vision Clinic, Department of Ophthalmology, St. Thomas' Hospital, Kings College, London, United Kingdom. dzr@londonvisionclinic.com
authors: Dan Z
authors: DZ
authors: Reinstein
authors: Timothy J
authors: TJ
authors: Archer
authors: Marine
authors: M
authors: Gobbe
mesh_terms: D000328:Adult; D000368:Aged; D003315:Cornea / Q000000981:diagnostic imaging*; D003319:Corneal Stroma / Q000000981:diagnostic imaging* / Q000601:surgery; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods; D054018:Lasers, Excimer / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D012086:Reoperation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013524:Surgical Flaps; D014463:Ultrasonography; D055815:Young Adult