Prolonged organ culture reduces the incidence of endothelial immune reactions.

PURPOSE The number of antigen-presenting cells decreases during organ culture of corneoscleral discs. This might result in a decrease of immune reactions with increasing duration of organ culture. To investigate this hypothesis, we performed a retrospective analysis of all penetrating keratoplasties that were consecutively performed over the last 5 years.PATIENTS AND METHODS All cases of penetrating keratoplasties (n=1006) were divided into two groups, with the division made at the median of the storage time (21 days). These two groups were compared by a Cox proportional hazards survival model regarding the incidence of endothelial immune reactions, clear graft survival, and chronic endothelial cell loss following penetrating keratoplasty considering patient's age, donor's age, and risk situation as co-variates.RESULTS We observed statistically significantly fewer endothelial immune reactions (20.1% (95% confidence interval 15.5-24.5%) after 2 years) in the group with a storage time of more than 21 days compared with the group with a storage time of <21 days (26.5% (95% confidence interval 21.6-31.2%) after 2 years). However, the duration of organ culture did not have a statistically significant effect on clear graft survival or chronic endothelial cell loss.CONCLUSION Our results demonstrate that an increased duration of organ culture leads to a lower incidence of endothelial immune reactions following penetrating keratoplasty. However, we do not recommend increased storage times in general as overall graft survival did not improve. The reason for this apparent paradox may be that the endothelial cell count decreases during storage time.