June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
OCT topography: A novel, non-invasive method to analyze the Epithelium- Bowman’s interface in normal and keratoconic eyes
Author Affiliations & Notes
  • RUSHAD SHROFF
    REFRACTIVE AND CORNEA, NARAYANA NETHRALAYA, New Delhi, India
  • Rachana C S
    IBMS, Narayana Nethralaya Foundation, Bangalore, India
  • Mathew Francis
    IBMS, Narayana Nethralaya Foundation, Bangalore, India
  • HIMANSHU MATALIA
    REFRACTIVE AND CORNEA, NARAYANA NETHRALAYA, New Delhi, India
  • Rohit Shetty
    REFRACTIVE AND CORNEA, NARAYANA NETHRALAYA, New Delhi, India
  • Abhijit Sinha Roy
    IBMS, Narayana Nethralaya Foundation, Bangalore, India
  • Footnotes
    Commercial Relationships   RUSHAD SHROFF, None; Rachana C S, None; Mathew Francis, None; HIMANSHU MATALIA, None; Rohit Shetty, Narayana Nethralaya Foundation (P); Abhijit Sinha Roy, Narayana Nethralaya Foundation (P), SIBAC grant, Indo-german science and technology centre, Germany (F)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 2442. doi:
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      RUSHAD SHROFF, Rachana C S, Mathew Francis, HIMANSHU MATALIA, Rohit Shetty, Abhijit Sinha Roy; OCT topography: A novel, non-invasive method to analyze the Epithelium- Bowman’s interface in normal and keratoconic eyes. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2442.

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

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Abstract

Purpose : To quantify keratometry and wavefront aberrations of the anterior corneal surface (ACS) and Epithelium-Bowman’s layer interface (EBI) using anterior segment optical coherence tomography (OCT) in normal and keratoconic (KC) eyes

Methods : In this study, 25 normal and 25 KC eyes were retrospectively analyzed using undistorted OCT B-scans (12 scans) and Pentacam HR. Axial and tangential curvatures for OCT was calculated from the detected ACS and EBI edges on the B-scans. Similarly, curvatures of the same ACS were obtained from Pentacam (OCULUS Optikgerate Gmbh, Germany). Wavefront aberration was also analyzed by ray tracing and 6th order Zernike analyses on OCT (ACS and EBI) and Pentacam data (ACS only). Intra-class correlation coefficient (ICC) was used to assess agreements between the surfaces and between the devices. Paired t-test and ANOVA was used for statistical comparisons.

Results : ICC showed comparable outcomes for ACS curvatures and aberrations between OCT and Pentacam (>0.93 for keratometry and >0.7 for aberration). However, most of the axial and tangential curvatures for OCT EBI (Fig b) were steeper than the OCT ACS (Fig a). Paired comparison of ACS vs. EBI on normal eyes (Table 1) showed significance difference in defocus (p=0.01), spherical aberration (p=0.02) and astigmatism 0<span style="font-size:11px; line-height:17px"> </span>(p=0.001) between OCT ACS and OCT EBI. Similarly, KC eyes showed significant difference in steep axis (p=0.002),max keratometry (p=0.001), coma 90 (p=0.01), astigmatism 0(p=0.004), lower order (p=0.01) and higher order(p=0.02) root mean square (RMS) of aberrations (Table 2). Within the normal and KC eyes group, difference between some of the EBI and ACS parameters achieved statistical significance (Table 3). Some of these parameters were steep axis (p=0.01) and max keratometry (p=0.02), coma 90<span style="font-size:11px; line-height:17px"> </span>(p=0.03), lower order RMS (p=0.02) and higher order (p=0.04) RMS of aberrations (Table 3).

Conclusions : This study presents a novel, non-invasive method for “virtual de-epithelization” using OCT, where no physical removal of epithelium is required. Significantly steeper EBI than the ACS was measured with OCT. This tool can be useful for preoperative planning of trans-epithelial procedures and customized corneal collagen crosslinking.

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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