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Epithelial subtraction OCT topography: a novel method and its translational relevance

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Session Details

Session Title: LASIK and Imaging

Session Date/Time: Tuesday 10/10/2017 | 14:00-15:20

Paper Time: 14:37

Venue: Room 4.1

First Author: : A.Bajaj INDIA

Co Author(s): :    R. Shetty   A. Roy   R. Shroff              

Abstract Details


To study topography and aberrations of the corneal surface and Epithelial-Bowman’s interface using AS-OCT based indices.


Narayana Nethralaya, Bangalore, India


25 normal and 25 KC eyes were retrospectively analyzed using undistorted OCT B-scans (12 scan) and Pentacam HR. Axial and tangential curvatures for OCT was calculated from the detected Anterior corneal surface (ACS) and Epithelium Bowman’s Interface (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). Paired t-test and ANOVA was used for statistical comparisons.


Higher and lower order aberrations were greatest for the EBI followed by the anterior corneal surface in KC eyes (p<0.05). Kmax of the interface was steeper than the anterior corneal surface by 1D (p<0.05). Paired comparison of ACS vs. EBI on normal eyes showed significance difference in defocus (p=0.01), spherical aberration (p=0.02) and astigmatism 0◦ (p=0.001) between OCT ACS and OCT EBI.


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 crosslinking.

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