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F. Beer, A. Wartak, N. Pircher, S. Holzer, J. Lammer, G. Schmidinger, B. Baumann, M. Pircher, C. Hitzenberger:
"Mapping of Corneal Layer Thicknesses With Polarization-Sensitive Optical Coherence Tomography Using a Conical Scan Pattern";
Journal of the Acoustical Society of America, 59 (2016), 6; 3557 - 3562.

PURPOSE. We demonstrate segmentation and mapping of corneal layers (epithelium, Bowman´s
layer, and stroma) across the entire cornea (limbus to limbus), using additional contrast
provided by polarization-sensitive optical coherence tomography (PS-OCT) and analyze the
reproducibility of the procedure.
METHODS. A custom built PS-OCT system operating at 1045 nm central wavelength with
conical scanning was used for image acquisition. Conical scanning allows for almost
perpendicular beam incidence on the corneal surface and provides good signal quality over
the entire field of view. Epithelium, Bowman´s layer, and stroma were segmented using the
additional contrast provided by PS-OCT. Thickness maps were computed and analyzed in
sectors. Both eyes of 20 healthy volunteers were imaged at least three times to test this
method and to quantify reproducibility.
RESULTS. Thickness maps of the epithelium show significant (P < 0.001) superior thinning and
an inferior thickening. Bowman´s layer appears homogeneous within the central 7 to 8 mm
diameter of the cornea and gets thinner toward the periphery until this layer disappears
between 4 and 5.5 mm eccentricity from the center. Intersubject variations of the measured
thicknesses of epithelium (coefficient of variation [CV] ~8%), Bowman´s layer (CV~25%), and
stroma (CV~10%) were observed. Very good reproducibility of thickness measurements of
epithelium (CV < 3%), Bowman´s layer (CV < 5%), and stroma (CV < 2%) was found.
Furthermore, a significant correlation (P < 0.001) between layer thicknesses of the right and
left eyes of the same subject was found.
CONCLUSIONS. PS-OCT with conical scanning is a feasible approach for determining thickness
maps of corneal layers on a large field of view with high reproducibility.

optical coherence tomography, polarization-sensitive imaging, cornea, corneal epithelium, Bowman´s layer

http://dx.doi.org/10.1167/iovs.18-25311

https://publik.tuwien.ac.at/files/publik_274129.pdf