title: Automated volumetric analysis of interface fluid in descemet stripping automated endothelial keratoplasty using intraoperative optical coherence tomography.
abstract: OBJECTIVE
  We demonstrated a novel automated algorithm for segmentation of intraoperative optical coherence tomography (iOCT) imaging of fluid interface gap in Descemet stripping automated endothelial keratoplasty (DSAEK) and evaluated the effect of intraoperative maneuvers to promote graft apposition on interface dimensions.
  
  
  METHODS
  A total of 30 eyes of 29 patients from the anterior segment arm of the PIONEER study was included in this analysis. The iOCT scans were entered into an automated algorithm that delineated the spatial extent of the fluid interface gap in three dimensions between donor and host cornea during surgery. The algorithm was validated against manual segmentation, and performance was evaluated by absolute accuracy and intraclass correlation coefficient. Patients underwent DSAEK using a standard sequence of maneuvers, including controlled elevation of IOP and compressive corneal sweep to promote graft adhesion. Measurement of interface fluid volume, en face area, and maximal interface height were compared between scans before anterior chamber infusion, after pressure elevation alone, and after corneal sweep with pressure elevation using dependent-samples t-test.
  
  
  RESULTS
  The algorithm achieved 87% absolute accuracy and an intraclass correlation of 0.96. Nine datasets of a total of 84 (11%) required human correction of segmentation errors. Mean interface fluid volume was significantly decreased by corneal sweep (P = 0.021) and by both maneuvers combined (P = 0.046). Mean en face area was significantly decreased by corneal sweep (P = 0.010) and the maneuvers combined (P < 0.001). Maximal interface height was significantly decreased by pressure elevation (P = 0.010), corneal sweep (P = 0.009), and the maneuvers combined (P = 0.010).
  
  
  CONCLUSIONS
  Quantitative analysis of iOCT volumetric scans shows the significant effect of controlled pressure elevation and corneal sweep on graft apposition in DSAEK. Computerized iOCT analysis yields objective measurements of interface fluid intraoperatively, which provides information on anatomic outcomes and could be used in future trials.
authors.affiliation: Cleveland Clinic Lerner College of Medicine, Cleveland Clinic, Cleveland, Ohio, United States Ophthalmic Imaging Center, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States.
authors.forename: David
authors.initials: D
authors.lastname: Xu
authors.affiliation: Ophthalmic Imaging Center, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States.
authors.forename: William J
authors.initials: WJ
authors.lastname: Dupps
authors.affiliation: Ophthalmic Imaging Center, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States.
authors.forename: Sunil K
authors.initials: SK
authors.lastname: Srivastava
authors.affiliation: Ophthalmic Imaging Center, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States.
authors.forename: Justis P
authors.initials: JP
authors.lastname: Ehlers
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001331:Automation; D003316:Corneal Diseases / Q000601:surgery; D003886:Descemet Membrane / Q000473:pathology / Q000601:surgery*; D057111:Descemet Stripping Endothelial Keratoplasty / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D041623:Tomography, Optical Coherence / Q000379:methods*
keywords: endothelial keratoplasty; interface; intraoperative; optical coherence tomography; volume
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