June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Quantitative Analysis of Epithelial and Total Corneal Thickness in Keratoconus using Sub-Micrometer Axial Resolution Optical Coherence Tomography
Author Affiliations & Notes
  • Kirsten Carter
    School of Optometry and Vision Science, University of Waterloo, Milverton, Ontario, Canada
  • Lacey Haines
    School of Optometry and Vision Science, University of Waterloo, Milverton, Ontario, Canada
  • Benjamin MacLellan
    Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
  • Olivera Kralj
    Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
  • Ahmed Gawish
    Systems Design Engineering Department, University of Waterloo, Waterloo, Ontario, Canada
  • Paul Fieguth
    Systems Design Engineering Department, University of Waterloo, Waterloo, Ontario, Canada
  • Luigina Sorbara
    School of Optometry and Vision Science, University of Waterloo, Milverton, Ontario, Canada
  • Kostadinka K Bizheva
    Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada
  • Footnotes
    Commercial Relationships   Kirsten Carter, None; Lacey Haines, None; Benjamin MacLellan, None; Olivera Kralj, None; Ahmed Gawish, None; Paul Fieguth, None; Luigina Sorbara, None; Kostadinka Bizheva, None
  • Footnotes
    Support  NSERC 312037, CIHR-CHRP 446387, CIHR-CPG 127791
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 3517. doi:
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      Kirsten Carter, Lacey Haines, Benjamin MacLellan, Olivera Kralj, Ahmed Gawish, Paul Fieguth, Luigina Sorbara, Kostadinka K Bizheva; Quantitative Analysis of Epithelial and Total Corneal Thickness in Keratoconus using Sub-Micrometer Axial Resolution Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3517.

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

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Abstract

Purpose : An important application of ultra-high resolution optical coherence tomography (UHR-OCT) is quantifying the thickness of the human cornea in corneal diseases such as keratoconus. The purpose of this prospective cross-sectional research project was to measure with high precision the epithelial and total corneal thickness in keratoconic and healthy subjects by using a sub-micrometer axial resolution OCT system.

Methods : Keratoconic (KC) subjects and healthy controls were recruited from the University of Waterloo School of Optometry and Vision Science Contact Lens Clinic. A total of 38 eyes were imaged from 10 male and 10 female KC subjects aged 41.6 ± 10.9 years (range: 24-55 years) and controls aged 41.4 ± 9.6 years (range: 27-52 years). The subjects were imaged with a research grade OCT system that provided 0.95 µm axial and < 3 µm lateral resolution in corneal tissue and an image acquisition rate of 34,000 A-scans/s. Volumetric OCT images were acquired from a 4mm x 1mm area in the cornea centered at the location of the minimum total corneal thickness as determined by Pentacam® topography. The OCT images were processed and analysed with custom image processing and segmentation algorithms developed by our research group. Epithelial thickness at the thinnest corneal location was also measured. Data was analysed using the Student’s t-test, with Statistica 12®.

Results : The mean total corneal thickness was 438 µm ± 38 µm, ranging from 356 µm to 489µm for the KC group, and 503 µm ± 29 µm, ranging from 442 µm to 556 µm for the healthy control group. The difference in the total corneal thickness between KC and control subjects was not significant (p=0.10). The epithelial thickness measured at the thinnest location of the cornea was 48 µm ± 31 µm, ranging from 26 µm to 75µm for the KC subjects, and 54 µm ± 3 µm, ranging from 50 µm to 60 µm for the control group. This difference was significant, p<0.0001.

Conclusions : The sub-micrometer resolution OCT system was capable of generating higher resolution images of healthy and KC corneas compared to the most advanced clinically available OCT technology. The higher axial resolution combined with a custom automatic segmentation algorithm allowed for more precise measurement of the epithelial and total corneal thickness, as well as more detailed visualization of the morphological changes in the KC cornea.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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