Factors influencing the decline in endothelial cell density after corneal allograft rejection

Corneal allograft rejection is one of the major causes of transplant failure. The purpose of the current study was to examine the decline in endothelial cell density (ECD) in patients experiencing allograft rejection, by comparing this decline with the normal evolution in patients who undergo penetrating keratoplasty (PKP) and to identify possible factors predictive of this endothelial cell loss after corneal allograft rejection.

In a case-control study of 45 corneas that underwent corneal allograft rejection, specular microscopy photographs taken within the shortest time preceding the onset of rejection and after the resolution of the rejection were analyzed.

The observed percentage loss of ECD in 21 (47%) corneas was not significantly greater than expected. A second group of 13 (29%) corneas showed a decline in ECD that was significantly greater than expected. Finally there were 11 corneas (24%) in which endothelial cells were no longer observable. The only two risk factors that reached statistical significance after multiple logistic regression analysis were a delay in diagnosis (a delay of >1 day yielded an odds ratio of 10.40; P=0.02) and a recipient age of more than 60 years (odds ratio, 6.95; P=0.04).

Corneal allograft rejection does not necessarily cause a higher than expected endothelial cell loss; almost half of the patients in this study showed a decline in ECD that is comparable to the decline in patients who undergo PKP and have an uneventful follow-up. The most important variable influencing the extent of endothelial cells loss is a delay in diagnosis and treatment.