Abstract
Purpose :
1) To evaluate the variation in corneal endothelial cell density (ECD), from center to far periphery, in unpeeled and peeled donor corneas. 2) To determine the impact of eccentric trephination on total endothelial cells in DMEK grafts.
Methods :
Paired donor corneas were obtained for evaluation. One randomized cornea from each mated pair was peeled for DMEK surgery using standard scuba technique while the mate was left unpeeled. Alizarin Red was used to stain the endothelial cells of all corneas. One image from the center and mid-periphery (2.5mm from center) was obtained for each cornea. For unpeeled corneas, 4 additional images from the corneal periphery (5mm from center) were obtained corresponding to the superior, nasal, inferior, and temporal quadrants of the cornea. For peeled corneas, 4 peripheral images were obtained corresponding to quadrants proximal, distal, clockwise, and counter clockwise to the graft hinge. Images were then masked and analyzed for ECD by a blinded reviewer using ImageJ software. ECD was then plotted as a function of radius and modeled using regression analysis. Numerical integration using Simpson's rule was then used to calculate the change in total endothelial cells as a function of trephination eccentricity across a series of different graft diameters.
Results :
20 corneas (10 pairs) were evaluated. Compared to central ECD, mean peripheral ECD was 10.0% greater in unpeeled corneas, and 7.5% greater in peeled corneas. There was no difference between peeled and unpeeled corneas in terms of mean central (p=0.98) and peripheral (p=0.58) ECD. There was no statistical difference between peripheral ECD in the different quadrants of unpeeled corneas and no statistical difference between peripheral ECD based on location relative to the graft hinge in peeled corneas. For a given graft diameter, total graft endothelial cells increases exponentially as a function of milimeters of eccentricity. For a standard 7.5mm DMEK graft, trephinating 2.25mm eccentrically yields 2.4% more endothelial cells. This affect is magnified further in larger grafts.
Conclusions :
Corneal ECD increases from the center to the periphery. There was no statistically significant decrease in peripheral ECD after DMEK peel compared to unpeeled mate corneas. Eccentric trephination increases the number of transplanted endothelial cells in a given graft size.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.