title: In Vivo Imaging and Morphometry of the Human Pre-Descemet's Layer and Endothelium With Ultrahigh-Resolution Optical Coherence Tomography.
abstract: To visualize in vivo and quantify the thickness of the posterior corneal layers: the acellular pre-Descemet's layer (PDL), Descemet's membrane (DM), and endothelium (END) in healthy subjects, using ultrahigh-resolution optical coherence tomography (UHR-OCT).
  
  
  
  A research-grade, 800-nm UHR-OCT system with 0.95-μm axial resolution in corneal tissue was used to image in vivo the posterior cornea in healthy subjects. The system offers approximately 98 dB sensitivity for 680 μW optical power incident on the cornea and 34,000 A-scans/s image acquisition rate. This study comprised 20 healthy subjects, aged 20 to 60 years. The thickness of the PDL, DM, and END layers was measured both with a custom, automatic segmentation algorithm and manually.
  
  
  
  The boundaries and structure of the posterior corneal layers were clearly visible in the UHR-OCT images. The average thickness was measured to be 6.6 ± 1.4 μm (PDL), 10.4 ± 2.9 μm (DM), and 4.8 ± 0.4 μm (END), which agrees well with published data from ex vivo studies. Both the END and DM thickness showed minor spatial variations, whereas the PDL showed up to 2× thickness change for different locations on the same cross-sectional corneal image or over the entire imaged region of the cornea.
  
  
  
  Our data indicate that all three layers of the posterior cornea can be clearly visualized in vivo and their thicknesses measured precisely with UHR-OCT. Although the PDL thickness showed large spatial variations, the thickness of the DM and END layers was consistent over the entire imaged region of the cornea.
authors.affiliation: Department of Physics and Astronomy University of Waterloo, Waterloo, Ontario, Canada 2School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada 3Systems Design Engineering Department, University of Waterloo, Waterloo, Onta.
authors.forename: Kostadinka
authors.initials: K
authors.lastname: Bizheva
authors.affiliation: School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Lacey
authors.initials: L
authors.lastname: Haines
authors.affiliation: Department of Physics and Astronomy University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Erik
authors.initials: E
authors.lastname: Mason
authors.affiliation: Department of Physics and Astronomy University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Benjamin
authors.initials: B
authors.lastname: MacLellan
authors.affiliation: Department of Physics and Astronomy University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Bingyao
authors.initials: B
authors.lastname: Tan
authors.affiliation: School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Denise
authors.initials: D
authors.lastname: Hileeto
authors.affiliation: School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Luigina
authors.initials: L
authors.lastname: Sorbara
mesh_terms: D000328:Adult; D000465:Algorithms; D003886:Descemet Membrane / Q000166:cytology*; D004728:Endothelium, Corneal / Q000166:cytology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007089:Image Enhancement; D008297:Male; D008875:Middle Aged; D041623:Tomography, Optical Coherence / Q000379:methods*; D055815:Young Adult