Examination of a Modified Graft Preparation Technique to Induce Double-Scroll Formation and Promote the Use of Younger Descemet Membrane Endothelial Keratoplasty Donor Tissue.

PURPOSE: The purpose of this study was to determine whether controlled balanced salt solution (BSS) bursts during graft preparation can safely promote formation of a double-scrolled Descemet membrane endothelial keratoplasty (DMEK) graft in younger donor tissue. METHODS: DMEK grafts prepared from young donor tissue (average age, 55 years; range, 39-66 years) were floated in BSS to spontaneously form scrolls (N = 10 pairs). Controlled BSS bursts were used to promote double-scroll (DS) formation in 1 member of each pair. Grafts were stained, preloaded, and shipped before cell viability analysis. After appropriate training, a less experienced technician performed this technique on 10 additional corneas. Outcomes measured for both technicians include the success rate for obtaining a DS, scroll conformation after shipping, and endothelial cell loss (ECL). RESULTS: There was no difference in ECL between grafts subjected to additional manipulation compared with unmanipulated mate grafts (observer 1: 15.2% ± 3.3% vs. 15.2% ± 4.4%, P = 0.99; observer 2: 16.3% ± 2.9% vs. 15.9% ± 4.5%, P = 0.8). A technician experienced with this technique had a 90% success rate, whereas a less experienced technician had a 70% success rate. The mean ECL of the 10 grafts manipulated by the less experienced technician was not significantly different from results obtained from the experienced technician (observer 1: 18.5% ± 6.0% vs. 15.2% ± 3.3%, P = 0.15; observer 2: 18.1% ± 5.6% vs. 16.3% ± 2.9%, P = 0.34). Scrolls maintained their conformation during shipping events. CONCLUSIONS: Double-scroll graft formation using controlled BSS bursts is a reliable technique that can be performed without causing additional damage to DMEK grafts. This technique may make graft unscrolling easier and can promote the use of younger donor tissue for DMEK.

Modified procedure for Loading "Flat" DMEK Grafts Into an Injector.

PURPOSE: The aim of this study was to determine whether loading a Descemet membrane endothelial keratoplasty (DMEK) graft using a drop-in procedure results in more endothelial cell loss (ECL) than the standard suction procedure. METHODS: Pairs of donor corneas with equivalent preprocessing endothelium were prepared using the standard protocol of our eye bank. One member of each pair was loaded into an injector using the standard suction protocol. The mate graft was loaded using a drop-in protocol, in which the edge of the graft was gently grasped with a forceps, lifted to the edge of the injector, and dropped inside. Grafts were evaluated for ECL and examined for grab marks or other loading-associated damage. RESULTS: There was no difference in mean ECL of grafts prepared for DMEK using the standard protocol (20.6% ± 4.5%) compared with that of mate grafts prepared using the drop-in loading protocol (19.5% ± 4.8%, P = 0.59). There was no consistent pattern of damage in the drop-in-loaded grafts, as grab marks or other tissue damage associated with the drop-in loading protocol were not consistently identified by a trained corneal surgeon. CONCLUSIONS: ECL was not significantly different in grafts prepared using a drop-in loading procedure compared with grafts prepared using the standard suction protocol. The drop-in loading protocol may be particularly useful to surgeons who load their own grafts and eye bank processing technicians who encounter a "flat" DMEK graft that does not scroll or a loosely scrolled DMEK graft.

Ink Retention and Endothelial Cell Viability After the Application of an Orientation Stamp Over an Air Bubble During Descemet Membrane Endothelial Keratoplasty Graft Preparation.

PURPOSE: To investigate stamp visibility and endothelial cell loss (ECL) after the application of an orientation mark to Descemet membrane endothelial keratoplasty (DMEK) grafts supported by an air bubble. METHODS: Eighteen DMEK grafts were prepared at an eye bank using a technique where an orientation mark was applied to the stromal surface of a DMEK graft that was supported by a small air bubble placed at the edge of the 2 endothelial surfaces of the graft. Grafts were evaluated at 2 and 5 days for stamp visibility and at 5 days with calcein-AM staining for ECL. Nine grafts underwent cross-country shipping, and the ECL of shipped and nonshipped grafts was compared using unpaired t test. RESULTS: All 18 DMEK grafts exhibited a single, solid, readily visible orientation mark 2 and 5 days after preparation with a mean ECL of 13.5% ± 4.9%. Shipping conditions had no effect on stain retention or ECL. CONCLUSIONS: The application of an orientation stamp to a DMEK graft over an air bubble in an eye bank setting results in a single, solid orientation mark that is readily visible within the period in which most eye bank-prepared tissue is used. This technique produces no further ECL compared with the methods where the orientation stamp is applied through a stromal window. Eye bank technicians and surgeons can be confident that this modified preparation technique results in transplant-quality DMEK grafts with the additional benefit of conserving the stromal cap for use in other anterior lamellar procedures, thereby making efficient use of donor tissue.

Optical Coherence Tomography Assessment of the Cornea During Corneal Swelling: Should the Term "Descemet Membrane Folds" Be Reconsidered?

PURPOSE: Previous work has suggested that Descemet membrane (DM) folds arise in response to corneal swelling. However, their origin has not been closely explored. In this study, we used optical coherence tomography to evaluate whether DM folds arise secondary to folds in the middle stroma. METHODS: Serial optical coherence tomography images of donor cornea pairs in deionized water were taken for each of the following corneal manipulations: 1) untreated, 2) DM and the endothelium removed, 3) excised in the region of the deep middle/posterior stroma, and 4) excised in the middle stroma. RESULTS: For intact corneas, increasing duration in deionized water was marked by a progressive increase in corneal thickness and number of folds along the posterior surface. With DM and the endothelium removed, a similar phenomenon was observed. In the third set of corneas, the plane of resection created a structural separation in the region of the deep middle/posterior stroma. Folds were seen originating anterior to the resection plane. For corneas with the posterior and part of the middle stroma removed, the typical folds on the posterior surface as seen in the previous conditions were not observed. Instead, less numerous and smaller irregularities of the posterior surface of the resection plane were present. CONCLUSIONS: Folds in DM associated with corneal edema originate in the middle and posterior stroma and are secondarily transmitted into DM. On the basis of the stromal origin of these anatomic changes, "stromal folds" should be considered a more accurate term to replace "Descemet membrane folds."