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

Abstract

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% 6 3.3% vs. 15.2% 6 4.4%, P = 0.99; observer 2: 16.3% 6 2.9% vs. 15.9% 6 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 6.0% vs. 15.2% 6 3.3%, P = 0.15; observer 2: 18.1% 6 5.6% vs. 16.3% 6 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.

An approach to reduce Descemet’s membrane scrolling: Relevance to Descemet’s membrane endothelial keratoplasty (DMEK)

“…Attempts at limiting, modifying or reversing the tightness and con guration (single or double) of the DM scroll have been made with enzyme treatment, 17 polymer coating, 18 or mechanical means. 14,15 Thus, the scrolling of the DM is both a friend and a foe. The scroll allows introduction of the tissue into the anterior chamber through a narrow entry wound but its unscrolling in the anterior chamber poses technical challenges and can lead to endothelial cell loss.…”

Double-Scroll Formation by Fluid Column Manipulation in Preloaded DMEK Grafts Prepared From Younger and Older Donor Tissue

“…This technique can be used without concern for producing increased ECL in grafts prepared from younger donor tissue and can be used with older donor tissue for surgeons who wish to weigh the risk of a slightly increased ECL against the benefit of an easily opened graft that may require less intraoperative manipulation. Along with double-scroll grafts that are formed from single-scroll grafts at the time of processing before loading into an injector, 42 surgeons now have multiple means of achieving a double-scroll graft that may ease the burden of graft unfolding. In addition, these 2 methods may encourage the use of grafts prepared from younger donor tissue, thereby expanding the DMEK donor pool.…”

“…Based on a previous study, 42 a sample size of 9 grafts per treatment arm was chosen to detect a 6.25% difference in total ECL as measured by calcein-AM staining between manipulated versus unmanipulated grafts in either older or younger donor cohorts with a confidence level of 90% and α = 0.05. An ECL of 16% ± 4% that was previously published by our group in a study that also used prestripped, prestained, and preloaded DMEK grafts was used in the calculation.…”

“…22,23 For each graft, 2 images were captured with an inverted fluorescent light microscope (Zeiss AxioVertA1 equipped with an Axiocam 202 Monochrome camera, White Plains, NY), merged into a single image with Adobe Photoshop Elements 14.0 (Adobe Systems, San Jose, CA), and analyzed using FIJI and Trainable Weka Segmentation as previously described. 22,24,25 Statistical Analysis Based on a previous study, 42 a sample size of 9 grafts per treatment arm was chosen to detect a 6.25% difference in total ECL as measured by calcein-AM staining between manipulated versus unmanipulated grafts in either older or younger donor cohorts with a confidence level of 90% and a = 0.05. An ECL of 16% 6 4% that was previously published by our group in a study that also used prestripped, prestained, and preloaded DMEK grafts was used in the calculation.…”

“…12 Recently, we presented a laboratory investigation of a technique for forming double-scroll DMEK grafts at the time of graft preparation and found that controlled bursts of BSS could be used to reliably form a double-scroll graft, and furthermore, that additional graft manipulation, loading, and ejecting a wider double-scroll graft did not significantly increase endothelial cell loss (ECL). 42 A technique for forming a double-scroll DMEK graft from a single-scroll graft by manipulating the fluid column within a Straiko modified Jones tube (SMJT) was presented as a means for achieving an easily opened DMEK graft immediately before surgery at the 2019 European Society of Cataract and Refractive Surgeons. 20 Clinical studies in which a similar technique was used to form double-scroll DMEK grafts from single-scroll grafts demonstrated the potential utility of the double-scroll graft because the use of the double-scroll graft resulted in shorter graft unfolding time with acceptable 6- and 12-month ECL.…”