Abstract
Abstract: :
Purpose: To use optical coherence tomography (OCT) images to detect for prior LASIK in eye bank donor corneas. Methods: OCT images of 29 donor corneas (24 control, 5 with known LASIK) were obtained using a custom built OCT system designed specifically for donor cornea imaging. All images were obtained non–invasively through the sterile donor cornea container. The OCT system operates at 1310nm wavelength and scans each cornea along eight meridians centered upon the apparent apex. The length of each radial scan was 7.6mm with 512 axial scans per radial scan. For each cornea, corneal edges were segmented using automated image processing, and the refractive power of the central 5mm was computed from the resulting corneal curvatures. Control corneas were preserved in Optisol GS and were prepared according to the standard operating procedures of the Cleveland Eye Bank. The refractive powers of the control corneas (8 pairs, 8 individual eyes) were compared with the refractive powers of five LASIK corneas (2 pairs, 1 individual eye) obtained from other national eye banks. Results: Four control and 1 LASIK corneas were excluded from analysis due to the presence of Descemet’s folds in the OCT images. All control corneas were preserved within 24 hours of donor death, were scanned within 48 hours of donor death, and had endothelial cell counts > 2000/mm2. The mean death–to–scan time for control corneas was 23 hours (range 7.8–43.8) and 101 hours (range 66.3–202.2) for LASIK corneas. LASIK flaps could not be seen upon slip–lamp examination or OCT imaging but were confirmed with histology in all cases. The anterior surface power was 67.51 ± 2.45 D (mean ± SD) in control corneas and 64.23 ± 2.67 in LASIK corneas. The difference was significant by t–test (p = 0.02), but there is some overlap. No significant difference was seen upon comparison of posterior power (in air), anterior – posterior power, and central (3 mm diameter) and peripheral (5–6.5 diameter) thickness and their difference. Conclusions: OCT is able to provide thickness and topography maps of donor corneas through their sterile eye bank containers. Anterior surface refractive power appears to be the best predictor of LASIK versus non–LASIK donor corneas and merits further investigation. Thickness mapping does not appear to be a sufficient test, possibly due to variable swelling during preservation.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: non-clinical • cornea: storage