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Surgeons should embrace challenge of improving outcomes with DMEK
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 Richard L. Lindstrom |
The transition over the last decade from full-thickness penetrating keratoplasty to one method or another of endothelial keratoplasty for the patient with endothelial dysfunction alone has been a revolutionary change for the corneal surgeon.
Most corneal surgeons have now traversed the learning curve for Descemet’s stripping endothelial keratoplasty (DSEK), and outcomes are generally excellent. In addition, eye banks have learned to prepare, preserve and transport tissue appropriate for DSEK in a reliable and reproducible manner. Tissue manipulation during surgery results in significant endothelial cell loss, but primary donor failure rates remain low and similar to PK. Failure of donor attachment with the need to re-bubble, especially in complex cases such as those with anterior chamber IOLs, tube shunts, peripheral sector iris loss and aphakia, remains annoying but manageable. Visual recovery is good, with most patients attaining 20/40 or better with a healthy macula. Still, the optics of the lamellar transplant interface, as appreciated for decades by experienced corneal transplant surgeons, reduce visual acuity and contrast sensitivity, making 20/20 outcomes rare.
As proud as we are of a well-done DSEK, patients often look better than they see. It is therefore not surprising that innovative surgeons continue to look for improvements in the technique of endothelial keratoplasty. There is no need to transplant 100 µm or more of corneal stroma as a carrier for the corneal endothelium. It is possible to strip Descemet’s membrane alone with its attached monolayer of endothelium from a donor cornea. The endothelium on its basement membrane carrier can be prepared, preserved and transported by advanced eye banks. Unfortunately. Descemet’s membrane is a basement membrane and quite elastic. It naturally rolls into a tube when stripped. In addition, it adheres to the recipient’s stroma less reliably. Therein lies the next challenge for corneal surgeons to master.
Learning to implant, center and permanently attach the endothelial layer in a Descemet’s membrane endothelial keratoplasty (DMEK) is no small challenge. On the negative side, intraoperative manipulation is more difficult and inadvertent detachments are frequent and more difficult to manage. On the positive side, when successful, visual recovery appears to be faster, and visual acuity and contrast sensitivity outcomes are superior. Patients see as good as they look.
We corneal surgeons and the eye banks that support us are embarking on another journey of learning to become experts in DMEK. While DSEK seemed to attract significant interest from the lower-volume corneal transplant surgeon, the transition to DMEK may well require a higher volume of cases to become expert. Nonetheless, if it proves to be better for patients, we ophthalmologists will learn how to do it and make it available. The jury is still out, but it is intuitive to me that the visual results of a well-done DMEK in expert hands will prove superior to DSEK. If so, in a few years, DMEK will dominate. In addition, there is significant interest and research into methods for transplanting the endothelial cell layer alone. In a decade, we will likely develop ways to transplant endothelium, epithelium and even limbal stem cells alone to the benefit of patients worldwide.
Innovation is relentless and accelerating in medicine. Sometimes, trying to keep up with the enormous challenge of continuous change in our field, I think it would be nice if the onslaught of new procedures to learn and master slowed a little. Then I remember the primary beneficiary, the patient with a significant visual disability, deserves no less than my best effort to provide the highest quality care possible, and I get back to work. The lifelong demand on the ophthalmic surgeon to acquire new knowledge and surgical skills is daunting at times, but also exhilarating for those who embrace change as opportunity.