BASIC INVESTIGATION Quantification and Patterns of Endothelial Cell Loss Due to Eye Bank Preparation and Injector Method in Descemet Membrane Endothelial Keratoplasty Tissues Julie M. Schallhorn, MD, MS,*† Jeffrey D. Holiman, CEBT,‡ Christopher G. Stoeger, MBA, CEBT,‡ and Winston Chamberlain, MD, PhD† Purpose: To evaluate endothelial cell damage after eye bank preparation and passage through 1 of 2 different injectors for Descemet membrane endothelial keratoplasty grafts. Methods: Eighteen Descemet membrane endothelial keratoplasty grafts were prepared by Lions VisionGift with the standard partial prepeel technique and placement of an S-stamp for orientation. The grafts were randomly assigned to injection with either a glass- modified Jones tube injector (Gunther Weiss Scientific Glass) or a closed-system intraocular lens injector (Viscoject 2.2; Medicel). After injection, the grafts were stained with the vital fluorescent dye Calcein AM and digitally imaged. The percentage of cell loss was calculated by measuring the area of nonfluorescent pixels and dividing it by the total graft area pixels. Results: Grafts injected using the modified Jones tube injector had an overall cell loss of 27% 6 5% [95% confidence interval, 21%– 35%]. Grafts injected using the closed-system intraocular lens injector had a cell loss of 32% 6 8% (95% confidence interval, 21%–45%). This difference was not statistically significant (P = 0.3). Several damage patterns including damage due to S-stamp place- ment were observed, but they did not correlate with injector type. Conclusions: In this in vitro study, there was no difference in the cell loss associated with the injector method. Grafts in both groups sustained significant cell loss and displayed evidence of graft preparation and S-stamp placement. Improvement in graft prepara- tion and injection methods may improve cell retention. Key Words: DMEK, injector, graft preparation, corneal trans- plantation (Cornea 2016;35:377–382) D escemet membrane endothelial keratoplasty (DMEK) was first described in 2002 by Melles, et al 1 as an alternative to Descemet stripping endothelial keratoplasty, and the first human transplant was performed in 2006. 2 The annual number of DMEK performed in the United States quadrupled between 2011 and 2014, but the total numbers still only amounted to approximately one eighth the number of Descemet stripping automated endothelial keratoplasties performed in 2014. 3 Several graft preparation and injection methods have been described. 4–12 In the United States, the modified Jones tube (Gunther Weiss Scientific Glass, Portland, OR) as described by Terry et al 10 and the closed-system intraocular lens (IOL) cartridge 5,9 have been available, albeit in off-label use. Recently, the DORC (DORC, Zuidland, the Netherlands) glass pipette injector has become available in the United States, but its current adoption in the United States is unknown. In Europe, where differing regulations make it easier to bring new technology to the market, the DORC glass pipette, 7 the Geuder glass injector (Geuder AC, Heidelberg, Germany), 12 and the Endoject (Medicel, Wolfhalden, Swit- zerland), 11 which operates similarly to the closed-system IOL cartridge, are all in use. There has been debate in the literature and in the community regarding the ideal material and propulsion mechanism for graft injection. 7,10 However, there are no published studies evaluating endothelial cell loss between different injector methods currently in clinical use. In this study, we aim to evaluate endothelial cell loss due to injector method with 2 popular injectors in the United States, the modified Jones tube and a closed-system IOL injector, the Viscoject 2.2 IOL injection system (Medicel). Both injectors are closed systems, meaning that pushing the plunger directly translates into increased pressure within the injector chamber. Any movement of the plunger induces fluid movement in the cartridge, which engages and propels the graft, thereby preventing contact with the plunger and providing an atraumatic injection environment. The closed IOL injector accomplishes this by means of a silicone plunger that snugly engages the rear of the plastic cartridge. METHODS The study was powered to detect a 10% difference in cell loss between injector groups with a confidence level of Received for publication August 24, 2015; revision received September 27, 2015; accepted October 2, 2015. Published online ahead of print November 19, 2015. From the *Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon; †Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA; and ‡Lions VisionGift, Portland, OR. Supported by the Lions VisionGift eye bank. The Casey Eye Institute is supported by an unrestricted grant from Research to Prevent Blindness. The authors have no conflicts of interest to disclose. Reprints: Winston Chamberlain, MD, PhD, Casey Eye Institute, Department of Ophthalmology, Oregon Health and Science University, 3375 SW Terwilliger Blvd, Portland, OR 97239 (e-mail: chamberw@ohsu.edu). Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. Cornea  Volume 35, Number 3, March 2016 www.corneajrnl.com | 377 Copyright Ó 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.