Single peripheral triangular mark ensuring correct graft orientation in DMEK.

Abstract

Dear Editor, The correct anatomical anterior–posterior orientation of the endothelial Descemet's membrane graft (EDM) is a significant but preventable cause of primary graft failure and graft detachment in DMEK (Descemet membrane endothelial keratoplasty) (Bachmann et al. 2010). The natural rolling tendency of the graft with the endothelial layer facing outwards does not necessarily lead to correct orientation of the graft in the anterior chamber during injection or unfolding (Bhogal et al. 2015; Wasielica-Poslednik et al. 2019). Different marking techniques could confirm the endothelial surface of the graft during DMEK. However, marking techniques using dyes like punched letters (Matsuzawa et al. 2017) or dots placed on the stromal side of the EDM (Wasielica-Poslednik et al. 2019) could lead to additional tissue manipulation, and a marking pen containing alcohol could be toxic (Ide et al. 2008). In addition, the use of a punch to trephine several asymmetrically positioned marks on the edge of the donor graft requires extra equipment (Bachmann et al. 2010; Matsuzawa et al. 2017). Bhogal et al. (2015) developed a simple and small triangular excision mark that requires no equipment other than the normal requirements for DMEK surgery. We adapted this technique at the end of the liquid-bubble preparation technique Klicken oder tippen Sie hier, um Text einzugeben.to further improve the postoperative outcome and evaluated the functional outcome and complication rate in patients receiving a DMEK 1 year before and 1 year after conversion to marking the EDM. Inclusion criteria for DMEK were exclusively Fuchs endothelial dystrophy with a follow-up for at least 3 months. The patients were divided into 2 groups; Group -M received the EDM graft without marking (n = 188). Then, a simultaneous switch to graft marking during preparation was performed for all surgeons, thus forming the +M group (n = 197). All graft preparations were performed using a standard liquid-bubble technique by 4 experienced surgeons. At the end, a triangle mark was cut on the graft margin with a scissor (Fig. 1, https://www.youtube.com/watch?v=dIa6DfHAHSI). Preoperative characteristics were comparable in the two groups. The preparation of the EDM was comparably adherent in both groups (8% both groups, p = 0.9) and led slightly more often to graft tears in the -M group (8% versus 4%, p = 0.2). The slightly higher rate of upside-down location intraoperatively in the +M group (7% versus 4%, p = 0.2) can be interpreted by the better recognition of the marking. In all cases, a graft turning was then performed intraoperatively. Poor vision through a severely decompensated cornea was comparable in both groups and resulted in 3 patients (2%) requiring graft turning postoperatively in the +M group despite marking. Overall, the postoperative graft turning (−M 9% versus +M 2%, p = 0.002) and Re-DMEK rate (-M 8% versus +M 2%, p = 0.01) was significantly reduced by switching to marking. Thereby, Re-DMEK was significantly associated with a graft turning (p < 0.001). There was no dependence on graft turning or Re-DMEK in relation to the surgeon (p = 0.9 and p = 0.8 respectively). The resulting postoperative outcome for the two groups was comparable for visual acuity, central corneal thickness and endothelial cell count (p = 0.2, p = 0.9 and p = 0.5 respectively) after a follow-up of 3 months. In conclusion, the single peripheral triangular mark is a simple and cost-saving supplementation for the EDM preparation with the liquid-bubble technique to ensure the correct orientation of the graft intraoperatively, resulting in significantly reduced graft turning and, therefore, reduced Re-DMEK rate. It might be a good alternative as it is considerably easy and fast to adapt by any DMEK surgeon and does not seem to result in significant endothelial cell loss due to the comparable endothelial cell numbers between the two groups.