Endothelial cell loss during penetrating keratoplasty

We studied the central donor endothelium of 27 clear, penetrating corneal transplants with the specular microscope before and after keratoplasty. We examined the donor corneas first, in vitro, while they were immersed in McCarey-Kaufman preservation medium before transplantation. This preoperative examination proved valuable for screening donor corneas, several of which were not used on the basis of the specular microscopic appearance alone. We examined the donor endothelium again within one week after keratoplasty and calculated the number of endothelial cells per square millimeter from photographs. The reproducibility of the counting method was acceptable. Comparison of the examinations before and after transplantation on each patient showed that, on the average, 23% of the donor endothelial cells were lost during keratoplasty. The 12 phakic transplants lost significantly more endothelial cells than did the 15 aphakic grafts (37% vs 12%). A possible explanation for the increased cell loss in phakic keratoplasties is the shallow anterior chamber present during the initial placement of the graft. Phakic grafts that were larger or had shorter time intervals between donor death and enucleation lost fewer cells. Aphakic transplants had larger postoperative corneal thicknesses than did phakic transplants.