Caroline Helwick

November 16, 2017

NEW ORLEANS — In patients requiring cornea transplant who have already had glaucoma surgery, Descemet membrane endothelial keratoplasty (DMEK) provides better outcomes than Descemet-stripping endothelial keratoplasty (DSEK), according to a comparison of the two approaches in eyes with previous trabeculectomy and/or tube shunt.

The patients who were evaluated in this study had "the sickest eyes that have ever been compared head to head" for these surgical approaches, said Shawn Lin, MD, MBA, from the University of California, Los Angeles. This population has not been adequately evaluated for outcomes after these procedures.

In this challenging patient population, DMEK offered faster visual recovery, better final visual acuity, and less secondary graft failure than DSEK, in this well-matched case-control study, according to Dr Lin.

Dr Lin, a third-year resident, presented the findings here at the American Academy of Ophthalmology (AAO) 2017 Annual Meeting. Most of the patients he described were treated by his research mentor and the study's senior author, Sophie X. Deng, MD, PhD, associate professor of ophthalmology at the Jules Stein Eye Institute at the University of California, Los Angeles.

Previous Work

Dr Deng and colleagues have been looking at this issue for years. She recently led an AAO-commissioned meta-analysis of 47 studies of DMEK that found DMEK to be superior to DSEK in terms of recovery rate, final vision, and graft rejection rate, but the patient population was not as challenging as post-glaucoma-surgery patients, Dr Lin pointed out.

In patients with glaucoma, the University of California, Los Angeles, team also reported worse visual outcomes and higher secondary graft loss after DSEK compared with persons with less complex eyes. They further demonstrated in 2017 that DMEK achieves good visual outcomes in this population.

In sum, DSEK is less technically challenging than DMEK, but has been found to produce worse final visual acuity, slower visual recovery, and a higher rate of graft rejection. The question is whether "in very sick eyes with tubes or a shunt," what is the head-to-head performance of these procedures? Dr Lin said.

DMEK vs DSEK in Well-Matched Cohorts

The case-matched retrospective cohort study compared outcomes with DMEK and DSEK among patients treated in the last 10 years. Investigators retrospectively reviewed the charts of 161 patients with DMEK and 597 patients with DSEK procedures, of whom 59 and 154, respectively, had prior glaucoma surgery.

From this group, researchers compiled two cohorts that were extremely well matched according to three criteria: preoperative visual acuity, surgical indication, and lens status; patient demographics, glaucoma status, and a few other variables were also matched. The final analysis was based on 47 DMEK patients and 47 DSEK patients.

"The two groups were very, very similar," Dr Lin emphasized. "We wanted to do that so that we are truly comparing apples to apples."

They looked at four major outcomes: visual acuity at various times, primary and secondary graft failure and rejection, complications, and postoperative glaucoma status (pressure elevation).

Visual Acuity Much Improved

"DMEK was remarkably better than DSEK in visual acuity," Dr Lin reported. "In fact, DMEK at 1 month was better than DSEK at 1 year and was significantly better than DSEK at all time points."

At 1 year, mean visual acuity was 1.10 log MAR units for DSEK and 0.70 for DMEK. Superiority was confirmed in virtually all components of the visual acuity subset analysis.

Table. Level of Visual Acuity Achieved for DMEK vs DSEK

Outcome DMEK (N = 47) DSEK (N = 47) P Value
20/20 - 20/40 at 6 months 32% 9% <.05
20/20 - 20/40 at 12 months 50% 13% <.05
Final visual acuity 20/90 20/250 NA

"Remember, these were very sick eyes: Baseline vision was 20/800. Other series that have compared these two approaches have often started with visual acuity of 20/80 or 20/100," Dr Lin emphasized.

Half the patients in the DMEK group achieved at least 20/40, which is important for attaining a driver's license, reading, and recognizing facial expression. Vision of 20/20 was achieved by 8% of the DMEK group, but the final visual acuity for DSEK was acuity 20/250, "which is legally blind," Dr Lin noted.

The average DSEK postcut graft thickness was 129 microns, and there was no correlation between thickness and visual acuity at 1 year, he added.

The rate of primary graft failure was the same (<3%), but secondary graft failure was significantly less common with DMEK (18% vs 3%; P = .015). Rejections also occurred less often after DMEK (<3% vs 6%), but the difference was not significant (P = .36). In DMEK, however, air injection/rebubbling was significantly more common (23% vs 10%; P = .0009).

Considering the good outcomes achieved with DMEK, Dr Lin suggested, "This is the surgery you should choose, despite its complexity and technical difficulty."

Depends on the Surgeon

Mark A. Terry, MD, director of cornea services at Legacy Devers Eye Institute in Portland, Oregon, commented on the findings for Medscape Medical News. "Dr Deng's group is doing exciting work. This is a retrospective study, but it is so well planned and so case-controlled: that's the strength of it. They matched the two conditions very well, in complex eyes, and they found differences in visual outcomes between the two procedures."

But these outcomes are very operator-dependent, he cautioned. "Like any new procedure, you don't want to do it [DMEK] until you feel accomplished in standard eyes. The data do show that if you are able to do DMEK well, which Dr Deng was obviously doing, you can get superior visual outcomes," he said, "but if you are not able to do DMEK well in complex cases, because of your level of experience, your technique, or whatever, then it's better to do a well-done DSEK than a poorly done DMEK."

Dr Shin and Dr Terry have disclosed no relevant financial relationships.

American Academy of Ophthalmology (AAO) 2017 Annual Meeting: Abstract PA076. Presented November 13, 2017.

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