July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
Co-/Cross-polarized channel supported limbus to limbus corneal Epithelium (ET-) and Bowman'S Layer Thickness (BLT) Mapping in keratoconic eyes and healthy eyes using large Field of View (FoV-) Polarization-Sensitive (PS-) Optical Coherence Tomography (OCT).
Author Affiliations & Notes
  • Niklas Pircher
    Ophthalmology, Medical University of Vienna, Vienna, Austria
  • Florian Beer
    Center for Med Pyhs & Biomed Eng, Medical University of Vienna, Vienna, Austria
  • Stephan Holzer
    Ophthalmology, Medical University of Vienna, Vienna, Austria
  • Jan Lammer
    Ophthalmology, Medical University of Vienna, Vienna, Austria
  • Michael Pircher
    Center for Med Pyhs & Biomed Eng, Medical University of Vienna, Vienna, Austria
  • Christoph K Hitzenberger
    Center for Med Pyhs & Biomed Eng, Medical University of Vienna, Vienna, Austria
  • Gerald Schmidinger
    Ophthalmology, Medical University of Vienna, Vienna, Austria
  • Footnotes
    Commercial Relationships   Niklas Pircher, None; Florian Beer, None; Stephan Holzer, None; Jan Lammer, None; Michael Pircher, None; Christoph Hitzenberger, None; Gerald Schmidinger, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 5727. doi:
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      Niklas Pircher, Florian Beer, Stephan Holzer, Jan Lammer, Michael Pircher, Christoph K Hitzenberger, Gerald Schmidinger; Co-/Cross-polarized channel supported limbus to limbus corneal Epithelium (ET-) and Bowman'S Layer Thickness (BLT) Mapping in keratoconic eyes and healthy eyes using large Field of View (FoV-) Polarization-Sensitive (PS-) Optical Coherence Tomography (OCT).. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5727.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Epithelial thickness (ET) thinning and irregularity in eyes with Keratoconus (KC) have already been shown in the last decade. Epithelial thinning above the cone and a reactive thickened area surrounding the cone represent specific findings in these studies. Today, there is evidence that the Bowman Layer (BL) shows signs of disintegration and pathological thinning in eyes with KC before the corneal stroma is affected. Aim of this study was to evaluate BL-changes using polarization sensitive (PS)-optical coherence tomography (OCT).

Methods : A custom built large Field of View (FoV)-PS OCT with a conical scanning optics design (axial resolution ~ 6 µm) was used to scan patients with unilateral KC. With this technique limbus-to-limbus measurements of the corneal epithelium and Bowman’s layer could be conducted. Two orthogonally polarized channels showed characteristic information of corneal tissue which enabled the differentiation of epithelium and BL.

Results : Twelve eyes of 6 patients with unilateral KC were scanned. A distinct differentiation of ET and BL was possible due to the different polarization properties of the tissues (Figure 1). The corneal epithelium showed characteristic changes by means of reactive thickening surrounding the cone (white arrow) and thinning above in the ectatic eye (yellow arrow). The BL in these eyes showed signs of disintegration [(Figure 2; intact BL (white arrow) and entirely disintegrated BL (yellow arrow)]. No differences in ET and BL integrity were found in the contralateral eye lacking signs of keratoconus in corneal tomography.

Conclusions : The advantage of limbus to limbus assessment of the corneal epithelium thickness (and the BL) is indisputable, since current studies only represent ET maps in a 6 mm central zone. In this study clear delineation of ET and BL thickness maps was possible in keratoconic and corresponding clinically normal eyes due to the different polarization properties of the tissues. However, the predictive value of ET maps and BL assessment as early screening methods remain to be elucidated in future studies.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

 

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