title: Reproducibility of Corneal Graft Thickness measurements with COLGATE in patients who have undergone DSAEK (Descemet Stripping Automated Endothelial Keratoplasty).
abstract: BACKGROUND
  The CorneaL GrAft Thickness Evaluation (COLGATE) system was recently developed to facilitate the evaluation of corneal graft thickness from OCT images. Graft thickness measurement can be a surrogate indicator for detecting graft failure or success. The purpose of this study was to determine the reproducibility of the COLGATE system in measuring DSAEK graft area between two observers.
  
  
  METHODS
  This was a prospective case series in which 50 anterior segment OCT images of patients who had undergone DSAEK in either eye were analysed. Two observers (MW, AC) independently obtained the image analysis for the graft area using both semi automated and automated method. One week later, each observer repeated the analysis for the same set of images. Bland-Altman analysis was performed to analyze inter and intra observer agreement.
  
  
  RESULTS
  There was strong intraobserver correlation between the 2 semi automated readings obtained by both observers. (r = 0.936 and r = 0.962). Intraobserver ICC for observer 1 was 0.936 (95% CI 0.890 to 0.963) and 0.967 (95% CI 0.942 to 0.981) for observer 2. Likewise, there was also strong interobserver correlation (r = 0.913 and r = 0.969). The interobserver ICC for the first measurements was 0.911 (95% CI 0.849 to 0.949) and 0.968 (95% CI 0.945 to 0.982) for the second. There was statistical difference between the automatic and the semi automated readings for both observers (p = 0.006, p = 0.003). The automatic readings gave consistently higher values than the semi automated readings especially in thin grafts.
  
  
  CONCLUSIONS
  The analysis from the COLGATE programme can be reproducible between different observers. Care must be taken when interpreting the automated analysis as they tend to over estimate measurements.
authors.affiliation: Singapore National Eye Centre (SNEC), 11 Third Hospital Avenue, 168751, SNEC, Singapore.
authors.forename: Melissa H Y
authors.initials: MH
authors.lastname: Wong
authors.forename: Annabel
authors.initials: A
authors.lastname: Chew
authors.forename: Hla M
authors.initials: HM
authors.lastname: Htoon
authors.forename: Beng H
authors.initials: BH
authors.lastname: Lee
authors.forename: Jun
authors.initials: J
authors.lastname: Cheng
authors.forename: Jiang
authors.initials: J
authors.lastname: Liu
authors.forename: Donald T
authors.initials: DT
authors.lastname: Tan
authors.forename: Jodhbir S
authors.initials: JS
authors.lastname: Mehta
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003315:Cornea / Q000473:pathology* / Q000601:surgery*; D016039:Corneal Transplantation; D057111:Descemet Stripping Endothelial Keratoplasty / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence / Q000379:methods*; D016896:Treatment Outcome