Eyeworld

EW CORNEA 30 April 2014 Expert outlines why he made the change from one procedure to another, including research he took part in E ndothelial surgery has evolved, with many developments in a rela- tively short span of time that have changed the treatment paradigm. Penetrating keratoplasty has moved on to other possibilities, including Descemet's stripping automated endothelial ker- atoplasty (DSAEK) and Descemet's membrane endothelial keratoplasty (DMEK). In a symposium that ex- plored surgeons' preferences for one form of cornea-related treatment to another, Friedrich Kruse, MD, Er- langen, Germany, presented the talk "I switched from DSAEK to DMEK." He said that there has been a great deal of debate about which technique to use, but he has made his choice. "What has been changing in our practice is that we have been moving entirely to DMEK from DSAEK," he said at the EuCornea symposium "What do I do differ- ently this year than last year?" The symposium was held prior to the 2013 European Society of Cataract & Refractive Surgeons Congress in Amsterdam. Why the switch In confronting the question of "Why should we move from DSAEK to DMEK?" Dr. Kruse said he was looking for better visual acuity, smaller cuts with less astigmatism, no sutures and no need for suture removal, low cost equipment, and the same instruments as those used in cataract surgery. "It's all about vision," he said. "The major reason why we think it's better to perform DMEK instead of DSAEK is because it ren- ders better visual acuity. Why is this? You only need a very small cut to deliver the graft, only 2.5 mm in contrast to DSAEK, which is a larger cut, so you have a problem of astig- matism. You don't need any sutures in DMEK. Your equipment basically costs nothing—you just need a razor blade and two forceps and maybe a trefoil." He said the question should still be asked because while DSAEK is a straightforward procedure to per- form, DMEK has been linked to technical issues. DSAEK is a much thicker graft, of about 150 μm, compared to the thin layer used in DMEK. "As we are talking about an evolution from a 500-μm to a 5-μm thick graft, it is the question of whether this is a good evolution or if the last step [in the evolution of procedures] is something we don't need. There is much debate about which technique to use," he said. He said he has performed DSAEK in many cases over a number of years with good postoperative outcomes. The cornea is clear and the visual acuity is good. However, as the grafts thicken, to 700 μm to 800 μm, the visual acuity is no longer as good in his hands, despite the fact the cornea remains clear. He and his colleagues decided to conduct a side-by-side comparison study of the two techniques to ex- amine data on this topic. The study, "Descemet's membrane endothelial keratoplasty versus Descemet's stripping automated endothelial keratoplasty," was published in the American Journal of Ophthalmology in 2012. Patients with the same donor age were selected for the study, along with similar storage duration and death-to-preservation time, and "most importantly," according to Dr. Kruse, the same endothelial cell count. "We tried to make the two populations similar," he said. They evaluated the outcome and endothelial cell survival in 38 eyes of 38 consecutive patients who underwent DMEK and completed 6 months of follow-up compared to 35 eyes of 35 consecutive patients undergoing DSAEK for Fuchs' en- dothelial dystrophy or pseudophakic bullous keratopathy. Among their results, they found that central corneal thickness "decreased from 652±92 μm before surgery to 517±45 μm 6 months after DMEK, and from 698±137 μm before surgery to 618±66 μm 6 months after DSAEK," according to the study. Also, best corrected visual acuity increased from "0.70±0.48 logMAR and 0.75±0.32 logMAR before surgery to 0.21±0.14 logMAR and 0.48±0.19 logMAR 3 months after DMEK and DSAEK (P<.001), respec- tively, and to 0.17±0.12 logMAR and 0.36±0.15 logMAR 6 months after DMEK and DSAEK (P<.001), respectively," Dr. Kruse and colleagues found. Rejection rates Ultimately, the answer to the ques- tion "Why should we move from DSAEK to DMEK?" in Dr. Kruse's opinion, is graft rejection, which he noted was a major reason for the switch. He cited a 2012 study published in Ophthalmology by Frank Price Jr., MD, and colleagues that examined the risk of corneal transplant rejec- tion. The study authors looked at 141 eyes treated with DMEK, which were retrospectively compared to cohorts of 589 DSEK cases and 30 PK cases treated at the same center and having similar demographics, follow-up, and indications. Dr. Price and colleagues found a highly significant difference be- tween DMEK and DSEK rejection rates—1 patient (0.7%) had a docu- mented rejection episode in the DMEK group compared to 54 (9%) in the DSEK and 5 (17%) in the PK group. In Dr. Kruse's experience, the rejection rates for DMEK have been remarkably low as well: "We have now performed more than 800 cases in DMEK, and we had two rejection episodes so far," he said. There are trade-offs with DMEK, Dr. Kruse said, and one is that more rebubbling is necessary in DMEK than DSAEK. "In other words, the grafts with DSAEK stick much better to the backside of the cornea than the grafts in the DMEK [group]," he said. There is a learning curve, and rebubbling is commonly needed during that curve, he said. EW References Anshu A, Price MO, Price FW Jr. Risk of corneal transplant rejection significantly reduced with Descemet's membrane endothelial keratoplasty. Ophthalmology. 2012 Mar;119(3):536–40. Tourtas T, Laaser K, Bachmann BO, Cursiefen C, Kruse FE. Descemet membrane endothelial keratoplasty versus Descemet stripping automated endothelial keratoplasty. Am J Ophthalmol. 2012 Jun;153(6):1082–90.e2. Editors' note: Dr. Kruse has no finan- cial interests related to his comments. Contact information Kruse: friedrich.kruse@uk-erlangen.de by Erin L. Boyle Physician: I switched from the DSAEK to DMEK procedure Slit lamp image of an eye one year after DMEK. The visual acuity was 20/20 at one month after surgery. Source: Gerrit Melles, MD, PhD

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