Eyeworld

43 EW FEATURE by Ellen Stodola EyeWorld Staff Writer MD, PhD, Netherlands Institute for Innovative Ocular Surgery (NIIOS), Rotterdam, the Netherlands, are cur- rently using Descemet's membrane endothelial keratoplasty (DMEK). They commented on the specifics of the technique, how it compares to Descemet's stripping automated endothelial keratoplasty (DSAEK), and when each procedure should be used. Since 1998, NIIOS has intro- duced concepts for posterior lamel- lar keratoplasty, Dr. Dapena said. In the U.S. these techniques were pop- ularized as deep lamellar endothelial keratoplasty (DLEK) and DSAEK. Since its introduction, DMEK has been gaining ground, but some still prefer DSEK K eratoplasty procedures have evolved over the years, with a number of breakthroughs in tissue handling, wound healing, and the ways the surgeries are per- formed. Mark Gorovoy, MD, Fort Myers, Fla.; Francis Price, MD, Price Vision Group, Indianapolis; Mark A. Terry, MD, Devers Eye Institute, Portland, Ore.; and Isabel Dapena, "In 1998, we described a tech- nique for selective transplantation of Descemet's membrane through a self-sealing 3.0 mm clear corneal incision, at that time tentatively named DMEK," she said. "Since then, the DMEK technique evolved into what we now know as the 'stan- dardized no-touch DMEK technique' surgery, which can be performed in reproducible steps and with hardly any direct contact with the tissue, which theoretically diminishes the potential damage of the donor endothelium during surgery." Dr. Price said the first endo- thelial keratoplasties were diffi- cult because part of the posterior stroma had to be dissected off, and the surgeon had to do a hand dissection of the donor and fit the pieces together. Descemet's stripping endothelial keratoplasty (DSEK) was a huge breakthrough, he said. The vision was the same but without the problem of slow wound healing or wound rupture postoperatively, and it was a lot easier and safer for patients. "DSEK at this time is still the standard of care in the U.S," Dr. Price said. Why DMEK? DMEK, which started being used around 2008, increases the degree of difficulty for the surgeon because it is just Descemet's membrane and endothelium, Dr. Price said. Initially, handling donor prep was a prob- lem, but he said that for many high volume surgeons, the donor loss rate is now less than 1%. "The initial advantage with DMEK was that the vision was bet- ter," he said. When you just transplant Descemet's and endothelium, you are not inducing any irregularity into the patient's cornea, Dr. Price said, but no matter how you cut a DSEK graft, there is always some irregularity with the way the stroma is cut. When he and his colleagues started DMEK, they were doing it for improved vision, but surgeons tend- ed to still favor DSEK. As data was collected on DMEK, it was shown that rejection rates were lower than for other options. Dr. Price has now done more than 1,700 DMEK procedures in his practice and has only seen 20 rejec- tions. He added that some surgeons are using the ultra-thin DSAEK grafts and are seeing fewer rejections, but not as few as with DMEK. Dr. Gorovoy is currently per- forming and teaching DMEK. The results with DMEK are so far excel- lent, and both DSAEK and DMEK are superior to penetrating keratoplasty, he said. "Obviously they both replace endothelium, but there's no stroma carrier involved in DMEK," Dr. Gorovoy said. The potential for 20/20 vision is well over 50% with DMEK, he said, estimating that this is likely around 20% with DSAEK. DMEK is the next step in the evolution of these procedures, Dr. Gorovoy said. "The problem is if you don't have a certain volume, you never get past the learning curve," he said. "I would say if you're doing DSAEK successfully and you're a low vol- ume surgeon, just keep doing what you're doing." DMEK provides better and faster visual rehabilitation than any of the other endothelial keratoplasty techniques, Dr. Dapena said. "In DMEK no expensive instru- ments or equipment are needed, so it can be performed in any clini- cal setting by almost any corneal surgeon with proper training," she said. "Furthermore, DMEK allows for a more effective use of corneal tissue because out of 1 cornea, 2 keratoplasties can be performed." Evolution and implementation of DMEK into practice The right eye had a DMEK just 6 days before this photo, and the vision is 20/20 without glasses. The left eye had a DSAEK 6 months before the photo, and the vision is 20/25 with a hyperopic glasses refraction. Source: Mark Terry, MD AT A GLANCE • When beginning DMEK, there is a learning curve, so using the procedure may be more beneficial for high volume surgeons. • There are a number of injection techniques that can be used in DMEK, including IOL injectors or other off-label injectors. Glass material is often deemed better than plastic for success. • The best candidates for DMEK are eyes with corneal edema but no alteration of the anterior segment. continued on page 44 April 2015 Corneal lamellar surgical procedures

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