title: Swelling of the human cornea revealed by high-speed, ultrahigh-resolution optical coherence tomography.
abstract: OBJECTIVE
  To evaluate the change in thickness of the anterior, stromal, and posterior corneal laminae in response to hypoxia-induced corneal swelling, by means of ultrahigh-resolution optical coherence tomography (UHR-OCT).
  
  
  METHODS
  A UHR-OCT system, operating in the 1060-nm range, was used to acquire in vivo cross-sectional images of human cornea with a 3.2x10-microm (axial x lateral) resolution in corneal tissue. Corneal edema was induced by inserting a thick, positive-powered, soft contact lens, over which the eye was closed and patched for 3 hours. Tomograms were acquired from eight non-contact-lens wearers. Baseline images were obtained before inducing corneal edema, immediately after removal of the patch and the lens, and then every 15 minutes for approximately 2 hours. All images were postprocessed with a segmentation algorithm to identify the laminae visible in the image. The apical thickness of the laminae (epithelium [EPI], epithelial-Bowman's membrane [Ep-BM] complex, stroma, and endothelial-Descemet's membrane [En-DM] complex) were determined at each time interval.
  
  
  RESULTS
  There was an interaction between time after removal of the hypoxic stimulus and deswelling of the layers (RM-ANOVA; P<0.001). The epithelial and stromal thickness reduced significantly with time (P=0.001; P<0.001, respectively), whereas the Ep-BM and En-DM complexes did not (P>0.50). All layers except the En-DM complex exhibited a biphasic pattern of recovery.
  
  
  CONCLUSIONS
  UHR-OCT showed regional differences in swelling due to hypoxic provocation. On removal of the hypoxic stimulus, the rate of recovery varied between layers, and all layers except the En-DM complex exhibited a biphasic recovery.
authors.affiliation: School of Optometry, Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada. nhutchin@uwaterloo.ca
authors.forename: Natalie
authors.initials: N
authors.lastname: Hutchings
authors.forename: Trefford L
authors.initials: TL
authors.lastname: Simpson
authors.forename: Chulho
authors.initials: C
authors.lastname: Hyun
authors.forename: Alireza A
authors.initials: AA
authors.lastname: Moayed
authors.forename: Sepideh
authors.initials: S
authors.lastname: Hariri
authors.forename: Luigina
authors.initials: L
authors.lastname: Sorbara
authors.forename: Kostadinka
authors.initials: K
authors.lastname: Bizheva
mesh_terms: D000328:Adult; D000465:Algorithms; D000873:Anthracenes; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects; D015715:Corneal Edema / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D003886:Descemet Membrane / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D020127:Recovery of Function; D041623:Tomography, Optical Coherence / Q000295:instrumentation* / Q000379:methods*; D055815:Young Adult
chemical_list: C546739:AnOV compound; D000873:Anthracenes