Descemet Membrane Endothelial Keratoplasty with Irregular-Edged Graft: A Salvage Method for Large Radial Graft Tears

Mehmet Cüneyt Özmen; Nilay Dilekmen; Erdem Yüksel; Bahri Aydın; Fikret Akata

doi:10.4274/tjo.39019

ABSTRACT

Large radial tears of donor Descemet membrane (DM) during the preparation of Descemet membrane endothelial keratoplasty (DMEK) grafts can make the trephination stage impossible because of small graft diameter. This results in irregular-edged grafts. In this study, we report two pseudophakic bullous keratopathy patients who underwent DMEK surgery with irregular-edged Descemet membrane (DM) grafts. Main outcome measures were preoperative and postoperative 1-, 3-, and 6-month best corrected visual acuity (BCVA), endothelial cell density (ECD) and central corneal thickness (CCT). Intraoperative and early postoperative complications were also evaluated. Both irregular-edged grafts were successfully implanted into the anterior chamber, unfolded, and attached to the posterior corneal stroma. Patients’ BCVA at 6 months was 1.0 (Snellen equivalent: 20/20) and 0.6 (Snellen equivalent: 20/32) respectively. Decrease in ECD at the last visit was 27% and 25%. CCT decreased from 723 μm and 850 μm to 530 μm and 523 μm, respectively. No intraoperative complications occurred except for the large radial Descemet membrane graft tears that developed during donor DM stripping. None of the cases needed a rebubbling procedure postoperatively. We have demonstrated that irregular-edged DM grafts can be successfully implanted for DMEK surgery with good clinical outcomes.

Keywords:

Descemet membrane endothelial keratoplasty, large radial tears, irregular-edged Descemet membrane graft

Introduction

Descemet membrane endothelial keratoplasty (DMEK) is the latest refinement of endothelial keratoplasty procedures. Providing an exact anatomical replacement of only what is removed, it gives the possibility of excellent visual acuity with shorter healing time as well as minimal risk of immunological rejection.^1,2 However, preparing the 15-µm-thick Descemet membrane (DM) graft is still a challenging issue and is sometimes complicated by surgeon- or donor-related DM graft tears and graft failure. Standardized techniques for graft preparation, surgical instruments designed for endothelial keratoplasty, and accumulating experience over time have led to a significant reduction of tissue loss. However, as the donor-related risk factors for failure in donor tissue preparation have not been clearly determined, the potential risk for radial DM tearing still exists. By pulling the torn flaps peripherally and skipping the trephination stage of the graft preparation technique described by Melles et al.,^3,4 these irregular-edged grafts can still be successfully implanted. In this study, we describe the clinical results of two eyes with pseudophakic bullous keratopathy treated with DMEK with irregular-edged DM graft.

Discussion

DM graft preparation for DMEK surgery has been standardized previously with very low rates of tissue damage due to preparation.^6,7 However it can be complicated with large radial tears, making the trephination and usage of DEC graft impossible. Especially if the graft is prepared by the surgeon prior to surgery in the operating room, radial tear risk increases due to time limitations and surgical stress. To reduce the surgical stress, the surgeon can use eye bank-prepared donor tissue or prepare the tissue days before the surgery. It has been shown that eye bank-prepared grafts and surgeon-prepared grafts do not differ in terms of graft survival outcomes. Both preparation methods have a 5% graft preparation failure rate due to strong adhesions between DEC and stroma.⁸ Although grafts prepared by the eye bank might have an advantage in decreasing the surgical stress, eye bank-preparation is more expensive compared to preoperative preparation. Even when the surgeon is preparing the graft days before surgery, the use of an extra corneal storage solution increases the total cost of the procedure. Radial tears in DEC grafts that are formed during preparation might increase in size during implantation and unfolding of the graft, resulting in dehiscence of the graft postoperatively.

This complication can be managed with a modification of standardized donor tissue preparation technique: rescuing the radial tears by pulling the flap peripherally, skipping the trephination phase, and implanting the irregular-edged graft. Recently, two studies have shown that partial DEC grafts can be implanted and may yield good clinical outcomes.^9,10 Since the risk of losing tissue is still the biggest concern of DMEK graft preparation, the modification we propose can be a salvage method for using grafts with large radial tears.

With irregular-edged grafts, large areas of denuded stroma with edema can be seen in the first postoperative months. Spontaneous resolution of focal edematous areas without DEC may be attributed to the migration of donor and/or recipient endothelial cells onto the denuded stroma.^9,10,11

Although two cases may not be enough to evaluate the potential clinical outcomes of irregular-edged grafts, our results seem promising to salvage grafts with large radial tears. These irregular-edged, non-uniform DM grafts might be successfully implanted for DMEK surgery with the potential for favorable clinical outcomes.

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