May 03, 2016
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S-stamp marking technique helps prevent inverted graft implantation in DMEK

Endothelial cell loss, re-bubbling and complication rates were similar in stamped and unstamped graft groups.

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A novel S-stamp marking method eliminated upside-down graft implantation in Descemet’s membrane endothelial keratoplasty, according to a study.

The technique may help surgeons perfect the DMEK technique and avoid complications, according to Peter B. Veldman, MD, the corresponding author.

“The most significant finding was that the incorporation of the S-stamp eliminated one of the primary causes of iatrogenic graft failure in DMEK, being upside-down graft implantation,” Veldman told Ocular Surgery News. “Historically, surgeons have had higher rates of upside-down grafts in their learning curve despite using other pre-existing orientation techniques.”

In addition, use of the S-stamp did not adversely affect clinical outcomes such as endothelial cell loss, Veldman said.

“Nor were other markers of outcome [affected], like re-bubble rate or early or late complications. Most significantly, reducing the rate of graft failure due to inverted graft implantation from around 10% to 0% markedly improved the outcomes for those patients who might have had an upside-down graft without the S-stamp,” he said.

“[The Ophthalmology] paper was the clinical outcome and follow-up of a paper that was published in Cornea in September [2015] demonstrating the S-stamping technique and detailing the in vitro validation of this technique. That paper demonstrated that there’s really minimal induced trauma to the graft by adding this orientation mark,” Veldman said.

Study design

The retrospective study included 133 eyes that underwent DMEK with S-stamped grafts and 32 eyes that underwent DMEK with unstamped grafts.

Surgery was indicated for pseudophakic bullous keratopathy in two cases and for Fuchs’ endothelial keratoplasty in the remaining cases.

Patients underwent DMEK using a standardized technique before and after the implementation of a dry ink gentian violet S-stamp applied to the stromal side of Descemet’s membrane.

“The eye bank technician would prepare the DMEK tissue and at that time, using the technique that we published, would add an S-stamp to the tissue, so when it arrives at the surgeon, almost all of the preparation work is done and the S-stamp is in place. It’s our job to get it into the eye in the proper orientation,” Veldman said.

Two attending surgeons and three fellows performed DMEK at a single site.

Results

The rate of 6-month endothelial cell loss was 31% in the stamped graft group and 29% in the unstamped graft group; the between-group difference was not statistically significant.

Preoperative endothelial cell density was 2,715 cells/mm2 in the unstamped graft group and 2,693 cells/mm2 in the stamped graft group. Postoperative endothelial cell density was 1,908 cells/mm2 in the unstamped graft group and 1,862 cells/mm2 in the stamped graft group. The between-group differences were not significant.

Four iatrogenic graft failures were reported in the unstamped graft group and one in the stamped graft group. Three of the failures in the unstamped graft group resulted from upside-down implantation. There were no upside-down grafts in the stamped group. The single graft failure in the stamped group resulted from non-adhesion attributed to an inward edge fold of a right-side-up graft.

Seventeen grafts in the stamped group and one graft in the unstamped group required re-bubbling, but the difference was not significant.

One graft experienced a rejected episode in each group; more frequent topical steroid dosing was used to successfully manage each rejection.

Preoperative logMAR best corrected visual acuity was 0.33 in the unstamped graft group and 0.27 in the stamped graft group. Postoperative BCVA was 0.11 in the unstamped graft group and 0.10 in the stamped graft group. The between-group differences in BCVA were not significant.

The S-stamp was still visible in a majority of eyes at 6 months but had no apparent effect on objective or subjective visual acuity. – by Matt Hasson

Disclosure: Veldman reports no relevant financial disclosures.