DMEK success following glaucoma surgery ‘surprisingly low’
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Physicians and patients should be aware of the likelihood of Descemet’s membrane endothelial keratoplasty graft failure and the need for repeat transplantation in the presence of previous glaucoma surgery, according to a study.
“We initially conducted a study evaluating early outcomes of DMEK in the setting of previous glaucoma surgery,” Nir Sorkin, MD, told Healio/OSN. The study showed good early outcomes but a possible trend toward increased rates of rejection and secondary failure beyond the first postoperative year.
“This drove us to investigate longer-term outcomes, which demonstrated a surprisingly low 4-year DMEK survival probability of 27% in the setting of prior glaucoma surgery, as well as high rejection rates,” Sorkin said.
Fifty-one eyes with a history of trabeculectomy or glaucoma drainage device implantation and later DMEK were included in a retrospective chart review and compared with a control group of 43 eyes with Fuchs’ dystrophy that underwent DMEK combined with phacoemulsification and IOL implantation. Mean follow-up was 37.9 months for the study eyes and 33.8 months for the control eyes.
The cumulative probability of graft survival in the study group was 75% at 12 months but only 27% at 48 months. In a subgroup of 32 eyes in the study group with prior glaucoma drainage device implantation, cumulative probability of graft survival was 72% at 12 months and 17% at 48 months. Both rates were statistically significantly lower than in the control group (P < .001), which was maintained at 88%.
The rate of endothelial cell loss at 48 months in the control group was 52% compared with 74% in the study group (P = .004).
Primary failure occurred in eight eyes in the study group, seven of which were related to graft detachment, and all were managed with subsequent surgeries. Secondary failure occurred in 24 eyes, with mean time to failure of 24.1 months.
“We are also debating whether we should adopt a more aggressive rejection prophylaxis regimen in those patients, given the high rejection rates,” Sorkin said.
Perspective
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Sorkin and colleagues confirm our worst fears — the primary problem with DMEK in eyes with prior glaucoma surgery is not intraoperative difficulty, but poor long-term survival, with only a quarter of grafts surviving 4 years, and one in five developing allograft reaction/graft rejection compared with one in 50 undergoing DMEK for Fuchs’ dystrophy.
Many of the study eyes were beset by significant comorbidities including angle issues, IOL problems and prior penetrating keratoplasty, so the presence of a glaucoma tube or bleb cannot, per se, be blamed entirely. At the very least, prior glaucoma surgery is a strong negative prognostic marker for long-term DMEK graft survival, and patients should be counseled appropriately: “There is a 50% chance your graft will need to be repeated in 2 years.”
Two additional points are worth mentioning: First, PK and DSAEK grafts do not appear to fare any better, with similar long-term survival data already reported. Second, while the short expiration date is certainly disappointing, many patients can be successfully reoperated with DMEK after a prior failed DMEK, every 2 or 3 years, over and over again. It is not ideal, but it works, and the only vision-preserving alternative may be a KPro.
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