Eyeworld

EW FEATURE 52 Highlights from ESCRS 2016 • December 2016 AT A GLANCE • The DMEK procedure can have a steep learning curve, but many argue that it offers faster visual recovery for patients, among other benefits. • DMEK is a good choice for standard cases, while DSAEK may be better when there are ocular comorbidities. • DSAEK is still the procedure of choice for many surgeons, although DMEK has been catching on more. by Ellen Stodola EyeWorld Senior Staff Writer aphakic eyes, unicameral eyes, in patients with a sutured posterior chamber implant, and in patients with a glaucoma filtering procedure or tube shunt. DMEK would be appropriate for standard cases, Dr. Tan said, where there is only moderate corneal edema. "In cases of severe corneal clouding like severe pseudopha- kic bullous keratopathy, very poor visualization of the AC means it could be very difficult to manip- ulate the donor scroll in the right orientation," he said. Poor donor control during the standard DMEK procedure also precludes this proce- dure, in which there are risks of the Descemet's membrane scroll enter- ing the vitreous cavity (in aphakic eyes) or exiting through a glaucoma drainage tube, or in deep chambers in vitrectomized eyes. "Currently DMEK is best suited for uncompli- cated cases of mild or early corneal DSAEK. "Graft preparation is done manually and requires skill and time with a risk of graft damage and tis- sue waste," he said. "Tissue handling and implantation are more difficult as this thin tissue does not unroll spontaneously and more frequently tends to detach from the posterior stromal wall in the early postoper- ative period." For this reason, the probability of a patient rebubbling after DMEK is greater than with DSAEK, Dr. Fontana said. When one technique is preferable over the other The preferred indication that Dr. Hannush uses for DMEK is in pa- tients who are pseudophakic who have Fuchs' dystrophy or pseu- dophakic cornea edema/bullous keratopathy. Dr. Hannush noted that DSAEK is preferred when there is a significant comorbidity. Specific indications for DSAEK include in rejection." He added that DSAEK is the technique more commonly per- formed in Europe, as well as in the U.S., as it can be done in all patients with endothelial decompensation with or without ocular comorbidities. Dr. Hannush uses both DMEK and DSAEK, depending on the situa- tion. He stresses to residents, fellows, and colleagues that the best way to argue for one technique over the other is if you do both. Dr. Tan currently performs DMEK for relatively uncomplicated cases and DSAEK for the rest of his cases, noting that it's about 50/50. "However, I think the learning curve of my hybrid DMEK procedure is about over, as my results have been good," he said. "I am now perform- ing DMEK in more complicated cas- es, such as post-vitrectomized eyes, aphakia, post-PK, etc., so the ratio is likely to change in favor of DMEK." DMEK versus DSEK/DSAEK DSAEK remains the primary proce- dure for the majority of EK surgeons, Dr. Tan said, with many still in the learning curve of DMEK. There are more surgical challenges and slightly higher complication rates with DMEK. "I do think the basic technique remains too challenging for some surgeons and certainly for more complicated cases," he said. Dr. Hannush said that DMEK offers certain advantages over DSEK/ DSAEK, notably quicker visual reha- bilitation, better visual endpoints, faster time to achieve visual end- points, lower risk of rejection, and lower risk of steroid-induced pres- sure elevation. However, he noted that the improvement over DSAEK is not as great as DSAEK's superiority over penetrating keratoplasty (PK). DMEK is the ultimate procedure for EK, Dr. Fontana said, as it selec- tively substitutes the diseased layer of the cornea with an equivalent healthy one. "With this technique, the cornea regains its physiological and anatomical thickness as well as its normal profile," he said. The advantages of DMEK over DSAEK are principally related to better and more predictable visual outcomes of one to two Snellen lines greater, absence of the postoperative refractive changes, and a reduced risk of rejection, Dr. Fontana said. However, he noted that DMEK is more technically difficult than T here are a number of endothelial keratoplasty (EK) techniques available to surgeons, including De- scemet's stripping endothe- lial keratoplasty (DSEK), Descemet's stripping automated endothelial ker- atoplasty (DSAEK), and Descemet's membrane endothelial keratoplasty (DMEK). This was an important top- ic of discussion at the 2016 Europe- an Society of Cataract and Refractive Surgeons (ESCRS) annual meeting To continue the conversation, EyeWorld spoke with Luigi Fontana, MD, PhD, Reggio Emilia, Italy, Rudy Nuijts, MD, PhD, Maastricht, Netherlands, Sadeer Hannush, MD, Philadelphia, and Donald Tan, MD, Singapore, about their preferred procedures, advantages of each, and what cases may be most appropriate for DSAEK or DMEK. Preferred procedure Dr. Nuijts' current preferred tech- nique is ultra-thin DSAEK, but he noted that he also uses DMEK. His team recently published the out- come of a randomized comparison of ultra-thin DSAEK vs. DSAEK that showed the superiority of ultra-thin DSAEK, providing one line better vision. "We are now running a mul- ticenter, randomized clinical trial comparing ultra-thin DSAEK and DMEK," he said. DMEK is being explored, with claims of more rapid visual recovery. He said it's important to see results from multiple centers. Dr. Fontana uses DMEK and ul- tra-thin DSAEK. "These are the tech- niques that provide better, faster, and safer visual rehabilitation with low risk of postoperative complica- tions, among them endothelial graft Preferred endothelial keratoplasty techniques Difference between DSEK and DSAEK M any surgeons have now transitioned to DSAEK, the automated version of DSEK, using a microkeratome. With DSEK, the graft is prepared manually by dissecting the donor cornea mounted on an artificial anterior chamber, Dr. Fontana said. "With this technique the stromal surface of the donor graft is irregular and the graft thickness is generally greater than the one produced with a microkeratome," he said. This technique, where tissues are provided to surgeons already cut and ready for implantation, has been abandoned in most developed countries, yet remains a valid option where a precut tissue or a microkeratome may not be available, Dr. Fontana said. The safety advantages of DSEK over traditional PK still hold true even in the presence of the not pristine graft interface provided with DSEK, he said. Dr. Hannush said particularly in the U.S., most surgeons use DSAEK rather than DSEK procedures, although he noted that the two terms are often used interchangeably. The cut is smoother with DSAEK, he said, and therefore it's likely to be more uniform and consistent with better vision. DSEK involves use of a manually dissected donor lenticule and is more difficult and tends to create a less even and consistent donor thickness, Dr. Tan said. Donor preparation was quickly modified to using a semi-automated microkeratome, the automated lamellar therapeutic keratoplasty unit (Moria Surgical, Antony, France), which cut the donor with a LASIK-type microkeratome mounted on an artificial AC maintainer, creating much more regular cuts of the cornea, he said. With preset thicknesses possible, this is now the standard DSAEK technique, and in most places, the donor is pre- cut in the eye bank and supplied to the surgeon, cutting down on surgical time.

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