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Thickness and Curvature Changes of Human Corneal Grafts in Dextran-Containing Organ Culture Medium Before Keratoplasty.

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 (±SD) at baseline (T0) was 727 ± 156 μm. It reached 581 ± 103, 506 ± 84, 472 ± 79, and 456±7 μm after 6, 12, 18, and 24 hours, respectively. After 12 hours, 83% of the final deswelling was achieved. The radii of curvature (±SD) at baseline (T0) were (posterior flat, posterior steep, anterior flat, and anterior steep) 6.6 ± 0.5, 6.2 ± 0.5, 7.7 ± 0.4, and 7.4 ± 0.4 mm, respectively. After 24 hours, the radii of curvature reached 6.8 ± 0.1, 6.6 ± 0.3, 7.6 ± 0.1, and 7.4 ± 0.2 mm, respectively.


CONCLUSIONS
The kinetics of the deswelling process in medium II follow a hyperbolic curve. Considering a CCT of 506 μm at T12, we assume that a time interval of 12 hours in medium II might be enough for clinical purposes. This result might help to keep storage in medium II as short as possible to escape potential toxic effects of dextran in medium II. The radius of curvature does not seem to change within 24 hours for all measured surfaces.