The belief that corneas that have been preserved for > 7 days are not viable for transplantation is not based on evidence, says Jonathan Lass, MD. In fact, he led a study that found corneas can be preserved safely for 11 days without negative impact on the success of transplantation. In the Cornea Preservation Time Study, funded by the National Eye Institute, Lass and other researchers looked at 3-year graft success rates among 1,090 participants (1,330 eyes) who underwent transplantation via Descemet’s stripping automated endothelial keratoplasty by 70 surgeons at 40 surgical sites. Most of the patients had Fuchs’ endothelial corneal dystrophy, a progressive disease.
The researchers were “unable to conclude” that the success rates were the same for corneas preserved for 8 to 14 days, versus up to 7 days (92% vs 95%). However, they found that much of the difference between the groups was accounted for by patients receiving corneas preserved for 12 to 14 days.
In a separate analysis, the researchers looked to see if differences in corneal preservation time affected endothelial cell loss after 3 years. They found that corneas preserved for up to 7 days had a 37% loss of cells versus 40% in those preserved for 8 to 14 days. A closer look at the data showed that the effect of corneal preservation time on the loss of endothelial cells was comparable from 4 to 13 days.
Dr. Lass emphasizes that while patients who received the older corneas had lower success rates, even those success rates were “impressively high” at 89%.
Donor corneas are not in short supply in the U.S. Outside the U.S., however, corneal disease is the third leading cause of blindness and corneal donor tissue is scarce.