DLEK: Corneal Transplants without Stitches or Astigmatism

Using a newly developed procedure with refined technology and tools, a surgeon at the Froedtert & The Medical College of Wisconsin Eye Institute now regularly accomplishes corneal transplants that replace only the back layer of the cornea while leaving the remainder essentially untouched.

Deep lamellar endothelial keratoplasty (DLEK) went from the experimental phase to more common use about two years ago. For thousands of patients nationwide whose Fuchs' dystrophy or corneal edema severely limits their vision, DLEK offers several advantages over standard "full-thickness" corneal transplants. DLEK is most often completed with one or no stitches, without resulting astigmatism, and with greatly reduced recovery time.

"The cornea has a number of layers, but the most important layer in terms of its clarity is the very back layer known as the endothelium," said Steven B. Koenig, MD, Medical College Professor of Ophthalmology, the Eye Institute surgeon who performs DLEK. "The endothelium is a single cell layer thick and it covers the entire back of the cornea. It looks somewhat like a cobblestone street."

"These cells are responsible for keeping the cornea clear by pumping water out of the cornea. In certain diseases like Fuchs' dystrophy the cornea can start to accumulate water. When it accumulates water it starts to swell, and when it swells it becomes cloudy, and when it becomes cloudy you don't see clearly.

"Fuchs' dystrophy is seen more commonly in older women, but can be seen in men as well," Dr. Koenig said. "Causes of Fuchs' dystrophy are not fully known," he noted, "but heredity appears to be a major factor."

Advantages Over PK
"In the past what we did for these patients was to replace a full-thickness circular portion of the cornea," said Dr. Koenig. "That's called a penetrating corneal transplant (penetrating keratoplasty, or PK). That worked very well. Ninety percent of the grafts are clear, the majority of the patients saw well, but the recovery period was very, very long, often over a year. And oftentimes, even though the transplant stayed clear, patients would have problems with astigmatism, which referred to the fact that the cornea may have been warped or distorted.

"We also have issues (using PK) with removing stitches and strengths of the wound after a penetrating corneal transplant. With this new technique we don't replace the full thickness of the cornea. We simply replace the back layer that's diseased. The advantage of this technique is that we can do it through a tiny incision, sometimes self-sealing so we can do this even without stitches in some cases."

"With DLEK we are simply replacing the diseased back layer of the patient's own cornea, and we're replacing it with a brand new back layer from a donor who has a healthy back layer. We remove the patient's back layer through a small incision, fold the new donor layer like a taco, slip it into the eye and get it to unfold like a ship in a bottle. We use an air bubble to push it up against the back layer of the cornea."

Dr. Koenig estimated that nine times out of ten the new back layer of the cornea stays in place with DLEK. "When that happens," he said, "the new layer takes over the function of the patient's back layer."

"Now, instead of a full-thickness corneal transplant held in position by multiple stitches that requires over a year to heal, this new back layer will take over and within anywhere from a week to a month or so the cornea should clear and the vision usually returns pretty quickly," said Dr. Koenig. "And because we're not dealing with distortion of the cornea due to stitches that are too tight or too loose or wounds that can heal irregularly, we have very little induced astigmatism. So astigmatism is no longer an issue with these patients."

Big Work by Mini-Tools (and Donors)
There are risks involved with DLEK, Dr. Koenig said, such as the potential for graft rejection, infection and problems with pressure within the eye that are basically the same as with other transplant procedures. But the major disadvantages of our standard corneal transplant, prolonged healing and astigmatism, are virtually solved when DLEK is used.

Dr. Koenig said that the great majority of DLEK procedures performed in Wisconsin are done at the Eye Institute, where more than 100 patients a year may benefit from the new treatment.

"This is a very exciting development, now the standard of treatment that we offer for Fuchs' dystrophy and for patients with corneal swelling," said Dr. Koenig. "The quality of vision is so much better with DLEK without the astigmatism, and nearly all patients will tell you that they are satisfied with the outcome. In fact, we have a number of patients who have had standard PK performed in one eye and DLEK in the other, and nine times out of ten they'll tell us that there's no comparison."

Dan Ullrich
HealthLink Contributing Writer

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.