Purpose: To determine the changes of corneal thickness and curvature of human corneal grafts in organ culture medium II, containing dextran T500 6%, before keratoplasty. Methods:We examined the tomography of 24 corneas from our eye bank transferred from medium I into medium II. Images were repeated hourly during 24 hours using an anterior segment optical coherence tomography. The central corneal thickness (CCT) was measured with the manual measurement tool of the anterior segment optical coherence tomography. The radii of curvature (anterior flat and steep and posterior flat and steep) were measured with a MATLAB self-programmed software for "sterile donor tomography."Results: The mean CCT (6SD) at baseline (T0) was 727 6

Background and Objective Sterile donor tomography enables the detection of corneal tissues with refractive anomalies. The aim of this study was to determine the curvature and thickness of donor corneas to support proper selection in the eye bank. Methods 704 donor corneas (Klaus Faber Center, LIONS Eye Bank Saar-Lor-Lux, Trier/Westpfalz, in Homburg/Saar) were measured using the anterior segment optical coherence tomograph (AS-OCT) CASIA 2 (Tomey Corp., Nagoya, Japan). The corneoscleral discs were measured in their cell culture flask, which was positioned in a holder on the chin rest of the AS-OCT, after conversion to medium II (with 6% dextran T-500). The measured raw data were analysed and processed in MATLAB (MathWorks Inc., Natick, Massachusetts, USA), after which the refractive power of the steep and flat meridian at the anterior and posterior surface and the central corneal thickness (CCT) of the donor corneas were determined. Results values are expressed as mean x̅ ± standard deviation SD. Results The mean refractive power of the steep/flat meridian at the anterior surface was 45.4 ± 1.8 D/44.0 ± 1.3 D, the corresponding values for the posterior surface were − 6.2 ± 0.3 D/− 5.9 ± 0.2 D, and the mean CCT was 616.3 ± 85.1 µm. Of the 704 (100%) measured donor tissues, 590 (83.8%)/670 (95.2%) donor corneas showed no anomaly beyond respectively x̅ ± 2 SD/x̅ ± 3 SD among the 5 examined parameters. 72 (10.3%)/23 (3.3%) donor corneas had only 1 anomaly, 26 (3.7%)/10 (1.4%) had 2 anomalies, 10 (1.4%)/1 (0.1%), 3 anomalies, 5 (0.7%)/0 (0.0%), 4 anomalies, and 1 (0.1%)/0 (0.0%), 5 anomalies. Conclusions AS-OCT provides an objective and sterile screening method to identify corneal tissues with curvature anomalies in order to further optimise donor selection in the eye bank. To avoid postoperative refractive surprises, donor corneas with a total refractive power that deviates > ± 3 SD from the mean should not be used for penetrating or anterior lamellar keratoplasty, but may be suitable for posterior lamellar keratoplasty (DMEK or DSAEK). In the future, sterile donor tomography could enable: (1) the harmonisation of donor and recipient tomography, which may minimise residual astigmatism for a particular donor-recipient pair; and (2) the improvement of IOL power calculation in a classical triple procedure by means of regression analysis between pre- and postoperative total refractive power of corneal grafts.

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