Peripheral Endothelial Cell Density in Descemet Membrane Endothelial Keratoplasty Grafts

To compare the variation in corneal endothelial cell density (ECD) from the center to the periphery in unpeeled and peeled donor corneas and to determine the impact of eccentric trephining on total endothelial cells in Descemet membrane endothelial keratoplasty (DMEK) grafts.

Mated donor cornea pairs were obtained. One cornea from each pair was peeled for DMEK, whereas the other was left unpeeled. Alizarin Red was used to stain the endothelial cells. High-resolution images at fixed magnification were obtained for the center, midperiphery (2.5 mm from the center), and the periphery (5 mm from the center). The cells were then counted, and ECD was calculated by a masked evaluator using ImageJ software. Regression analysis was then performed to evaluate the change in ECD as a function of radius (distance from the corneal center). The impact of eccentric trephining on total endothelial cells in a given DMEK graft was then calculated using numerical integration.

Ten pairs of corneas were evaluated. ECD increased by 1.4% (40.0 cells/mm) (P = 0.03) for peeled corneas and 1.8% (51.5 cells/mm) (P < 0.01) for unpeeled corneas for each millimeter from the center. There was no difference between peeled and unpeeled corneas in the mean central (P = 0.98) or peripheral (P = 0.35) ECD. Based on the increase in ECD as a function of radius, eccentric trephining of a 7.5-mm DMEK graft by 2.25 mm yields 0.95% more total endothelial cells per graft.

Corneal ECD increases from the center to the periphery in both peeled and unpeeled corneas. Eccentric trephining increases the number of transplanted endothelial cells per graft.