Routine Donor Tomography in the Eye Bank as Sterile Screening Method for Improved Graft Selection in Corneal Transplantation

Abstract

Purpose : To evaluate the efficiency of using anterior segment optical coherence tomography (AS-OCT) as a non-invasive and sterile screening method to detect corneal grafts with curvature and/or thickness abnormalities.

Methods : 227 routine human organ-cultured corneal buttons mounted in sterile tissue cultivation flasks were imaged using AS-OCT CASIA2 at least 24 hours after addition of 6% dextran T-500 (Medium 2). 3D volume data of the donor corneoscleral button within a 7.0 mm central zone were grabbed through the posterior surface of the cornea while the OCT system was aligned to capture the central part of the cornea. After pre-processing the data, an edge detection of the front and back surface of the donor cornea was performed using MATLAB. A sphero-cylindrical surface model was then fitted to the detected surfaces in order to determine the front and back radii of curvature and the central thickness.

Results : The mean steep/flat anterior radius of curvature was 7.4±0.3 (6.6–8.0) / 7.7±0.2 (7.1–8.8) mm, the respective values for the posterior surface were 6.6±0.2 (5.9–7.3) / 6.8±0.2 (6.2–7.5) mm and the mean central corneal thickness was 583.4±50.3 (452.5 – 769.8) µm. Abnormalities (beyond +/- 2 standard deviations) were found in 20 corneas (8.8%) for the front surface, 24 corneas (10.6%) for the back surface and 10 corneas (4.4%) for the thickness.

Conclusions : The AS-OCT provides an objective, sterile and semi-automated screening method to identify corneal morphological and refractive alterations (e.g. keratoconus, status post PRK/LASIK) in order to optimize corneal donor selection in the Eye Bank. Abnormal donors with sufficient endothelium may be used for posterior lamellar keratoplasty.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

Positioning of the cell culture flask on the chin rest using a holder in front of the AS-OCT

 

3D illustration of a donor cornea with holder and culture bottle wall