“Graft” Expectations

Descemet membrane endothelial keratoplasty (DMEK) is an effective technique for treating different causes of endothelial dysfunction in the cornea. However, patients with preexisting glaucoma may face risks, including accelerated graft failure post-DMEK.

WHAT IS DMEK?

DMEK involves the transplantation of the Descemet membrane and endothelium, which promotes faster visual recovery and less postoperative discomfort compared with traditional full-thickness corneal transplants. Special considerations must be taken into account in individuals with glaucoma, especially those who have had surgical procedures, such as trabeculectomy, stents, or shunts.

MECHANISMS OF ACCELERATED GRAFT FAILURE

Elevated IOP

Even moderate increases in IOP have been shown to negatively affect graft health, leading to quicker rejection or failure.¹

Lower Endothelial Cell Density and Compromised Function

The endothelial cell count in patients with glaucoma may already be compromised due to the disease itself, making the graft more susceptible to failure. Yu et al² noted a significant difference of approximately 200 cells/mm² compared with healthy, nonglaucomatous corneas.

IOP-Lowering Medications

Although a study by Janson et al³ reported no statistical correlation between the use of glaucoma medications and endothelial cell density, it was noted by Gagnon et al⁴ that patients who are on multiple glaucoma medications (ie, three or four) had lower endothelial cell counts compared with those taking fewer medications.⁵

Glaucoma Procedures

Endothelial cell damage and reduced endothelial cell density have each been observed in various types of glaucoma procedures.⁵ For instance, the implantation of a drainage device in the anterior chamber has been associated with progressive endothelial cell loss. Trabeculectomies can often lead to a shallow or flattened anterior chamber, which, in turn, can cause stress and damage to the endothelium. Additionally, microinvasive glaucoma surgeries have shown potential to harm the endothelium, particularly near the procedure site.⁵

IT’S A TRICKY BUSINESS

Careful screening and monitoring of patients at high risk of accelerated DMEK graft failure is crucial, not only for future management, but also for educating patients and setting post-procedure expectations. Advances in surgical techniques and postoperative care will be key in enhancing the success rates of DMEK in patients with glaucoma moving forward.