Abstract
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.
Key words
optical coherence tomography - sterile donor tomography - donor cornea - eye bank
- keratoplasty