Influence of temperature on corneas stored in culture medium. A comparative study using functional and morphological...

To investigate the influence of storage temperature on corneal swelling and on endothelial morphology in cultured corneas.

Forty-eight rabbit corneas were separated into four groups of 12. The corneas were stored in culture medium at 37 degrees (group 37), 34 degrees (group 34), 31 degrees (group 31) and 23 degrees (room temperature) (group 23), respectively. All the corneas were monitored by weight recordings on days 0, 1, 2, 3, 4 and 7. On day 7, corneas were prepared for scanning electron microscopy and endothelial cell counts were performed.

Lowering the temperature of the culture medium resulted in less swelling. Both temperature and storage time had significant effects on corneal swelling (p < 0.001). On day 7, the observed mean weight increase was 131.2%, 143.0%, 172.5% and 199.7% in groups 23, 31, 34 and 37, respectively. The estimated mean daily weight increase for the corneas were 2.6%, 4.0%, 9.1% and 16.0% in groups 23, 31, 34 and 37, respectively. Scanning electron microscopy showed an intact endothelial layer in all groups after 7 days and there were no statistically significant differences in endothelial counts between groups 23, 31 and 34. In group 37, the cell borders were difficult to distinguish after 7 days and no meaningful count could be performed.

The swelling rate of cultured corneas is significantly less at 23 degrees and 31 degrees than it is at 34 degrees and 37 degrees during the first week. This is most likely the result of a greatly increased barrier effect at lower temperatures. Whereas weight recording revealed profound differences between the groups, scanning electron microscopy and endothelial cell counting did not. The results support the hypothesis that storage at 37 degrees is not optimal in culturing corneas. Lowering the temperature below body temperature, and even lower than 31 degrees, results in less corneal swelling.