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Distinguishing healthy and keratoconic eyes using ultra high-resolution OCT based corneal epithelium thickness mapping

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Session Details

Session Title: Imaging Anterior Segment

Session Date/Time: Sunday 08/10/2017 | 16:00-18:00

Paper Time: 17:22

Venue: Meeting Center Room I

First Author: : N.Pircher AUSTRIA

Co Author(s): :    S. Holzer   R. Werkmeister   F. Schwarzhans   J. Lammer   D. Schmidl   G. Schmidinger     

Abstract Details


More recently the corneal epithelium has been gaining significance pertaining to the development of screening methods for corneal ectatic diseases. To discover new predictive parameters in the diagnostics of diseases such as Keratokonus (KK) has utter priority with regard to early detection or avoiding severe complication such as post-LASIK ectasia. Aim of this trial was to evaluate differences in epithelium thickness (ET) maps between healthy eyes and eyes with KK and to investigate specific parameters.


Medical University of Vienna, Department of Ophthalmology and Optometry


Sixty-nine healthy eyes and 36 eyes with KK were scanned using a custom-built SD-OCT system with a theoretical axial resolution of 1.2 µm. To create ET maps three-dimensional volumes with a scan size of 7.5 x 7.5 x 1.0 mm were acquired and plotted with an individual colour scale representing microns. For quantification of epithelium irregularity the ratio between thinnest point and the diagonally opposing thickest point of the epithelium was calculated (Rtt). Furthermore, the mean ET in 17 subsectors [central (2mm diameter) and 4 sectors temporal superior/inferior and nasal superior/inferior)] of a 5mm diameter zone were evaluated.


Mean±SD in KK and healthy eyes was Rtt: 0.76±0.09 and 0.93±0.04 (p<0.05), thinnest/thickest point 38.50 ± 5.11 µm/56.78 ± 5.50 µm and 46.80 ± 3.27 µm /54.00 ± 3.38 µm in healthy eyes (p<0.05), mean central ET: 46.25 ± 4.56 µm and 50.91 ± 3.66 µm in healthy eyes (p<0.05). Statistically significant ET-differences were also found in 4 subsectors of four quadrants with the highest thinning in the inferior temporal subsector (temp_inf; 43.93 ± 4.96µm). In contrast, healthy eyes showed a homogenous distribution. 66% of eyes with KK showed a “doughnut” profile.


The OCT used in this trial offers the advantage of both, a non-contact method and a very high axial resolution. Determined parameters with the highest potential of diagnostic discrimination between eyes with Keratoconus and healthy eyes were in descending order: Rtt (AUC: 0.979; cut-off: 0.85), mean thinnest point (0.928; cut-off: 41 µm) and mean temp_inf (AUC: 0.898; cut-off: 45 µm). Epithelial thickness irregularity and asymmetry seems to be the most important diagnostic factor when comparing eyes with KK and healthy eyes.

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