Imaging of corneal scars using polarisation sensitive OCT

Session Details

Session Title: Anterior Segment Imaging II

Session Date/Time: Tuesday 25/09/2018 | 08:00-10:30

Paper Time: 08:36

Venue: Room A4

First Author: : S.Holzer AUSTRIA

Co Author(s): :    F. Beer   N. Pircher   G. Schmidinger   M. Pircher   C. Hitzenberger   J. Lammer     

Abstract Details

Purpose:

Corneal scars due to infectious, traumatic or other origin affect people´s vision and therefore the quality of life. Imaging these pathologies and detecting their location and full extent in detail is complicated and reaches technical limits. Purpose of this study was to assess the exact extent and layer penetration of corneal scars using polarization sensitive OCT (PS-OCT) based on altered birefringent properties of corneal collagen scar tissue.

Setting:

Medical University of Vienna, Dept. of Ophthalmology and Optometry Medical University of Vienna, Center for Medical Physics and Biomedical Engineering

Methods:

After comprehensive ophthalmic examination of the patients’ eyes, images of corneal scars due to trauma, infectious diseases, hereditary or unkown origin were acquired using a CASIA 2 OCT. A custom built Swept Source PS-OCT (λ=1045nm, scan time <2sec) was used to generate limbus-to-limbus wide field volume scans of the cornea. For acquisition a raster scan pattern using conical scanning optics design was introduced to compensate for the corneal curvature. Assessed parameters included corneal layer thickness, area and depth of scarred corneal tissue. Additional polarization-sensitive parameters included localized change of retardation and axis orientation, bowman layer segmentation and epithelial thickness maps.

Results:

8 patients were included in this pilot study. Using PS-OCT image contrast could be improved compared to the commercially available OCT measurements. Using two orthogonally polarized channels (cross and co-polarized) layer morphology could be defined more precisely and more valid segmentation of epithelium, bowman´s membrane and stroma could be achieved.

Conclusions:

Anterior segment PS-OCT together with a conical scanning optics significantly improved details on the location, extent and depth of corneal scars. Additionally, specific topographic maps of not just the corneal surface but individually segmented epithelium and bowman’s layer is now feasible within one imaging process. This combined information might be beneficial for planning a more individualized treatment of corneal scars using phototherapeutic keratectomy or lamellar keratoplasty.

Financial Disclosure:

-