Optimizing the deswelling process of organ-cultured corneas

During deswelling of organ-cultured human corneas, endothelial cell loss occurs. Therefore, it is necessary to minimize the deswelling time and achieving an optimal central corneal thickness (CCT) of approximately 550 microm at the same time. We investigated the minimal deswelling time necessary and analyzed endothelial cell loss.

Fifty-eight human corneas were stored between 13 and 81 days in organ culture. CCT was measured by optical coherence tomography. Measurements were performed before preparation, during culturing, before deswelling, and after varying deswelling periods (1-72 hours) using 5% dextran. Additionally, vital staining was performed in 6 human corneas to assess endothelial cell loss between 24 and 30 hours of deswelling. To evaluate absolute cell loss, endothelial cells were counted on human corneal pairs after 24 and 30 hours of deswelling.

After organ culture, mean CCT was 1194 microm. After 24 hours of deswelling in dextran-containing medium, mean CCT was 600 microm, whereas after 30 hours, mean CCT was 510 microm and hardly any corneas showed a CCT of more than 550 microm. Almost no further decrease in CCT was observed thereafter. No factors could be identified predicting the necessary deswelling time; however, paired corneas showed significant correlation of deswelling characteristics. We did not see any differences in endothelial cell loss 24 and 30 hours of deswelling or the ratio of living to dead endothelial cell counts.

Deswelling for 24 hours does not provide an optimal corneal thickness. Because endothelial cell loss does not increase between 24 and 30 hours of deswelling, a period of 30 hours is more suitable for obtaining sufficient corneal thickness.