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Endothelial keratoplasty continues to evolve toward greater achievements
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Endothelial keratoplasty has been one of the most remarkable advances in ophthalmology, rapidly evolving through progressive refinement and widely adopted all over the world. Today in the U.S., Europe and most parts of Asia, 90% of situations in which corneal transplantation is needed and the main problem is the endothelium are dealt with by endothelial keratoplasty techniques rather than full-thickness transplantation. It is particularly in the last 2 or 3 years that initial resistance to this surgery — which was considered a difficult procedure and not within everyone’s reach — has been decisively overcome. Nowadays, only very few corneal surgeons are unable to offer endothelial transplantation to their patients, either because they do not have the expertise or work in hospitals with limited facilities.
Endothelial keratoplasty was quickly adopted in the U.S., where Descemet’s stripping automated endothelial keratoplasty became the gold standard. In Europe, where many surgeons were DSAEK-skeptic, the true shift occurred when Descemet’s membrane endothelial keratoplasty entered the scene. Something similar to the U.S. happened in Asia, although more and more surgeons are now converting to DMEK. Although no precise data are available concerning the relative proportion of DSAEK and DMEK, my perception is that DMEK currently accounts for about 25% of the endothelial procedures in the U.S., approximately 50% in Asia and about 60% in Europe. DMEK here has definitely overtaken DSAEK, especially in larger centers, and the majority of high-volume cornea surgeons in Europe are carrying out DMEK.
Personally, I performed DSAEK for about 5 years and was happy enough to do this procedure, but not happy enough to do it in best prognosis cases, in which I still used full-thickness grafts because vision at the end was going to be better. As soon as I switched to DMEK, in 2008 to 2009, I abandoned penetrating keratoplasty completely. I still used DSAEK for about 2 years in selected cases of complicated aphakia or in the presence of anterior chamber lens. By the end of 2010, when I felt completely confident with DMEK, I abandoned other procedures, and now I perform DMEK in every single case. Personally I can no longer see reasons to perform DSAEK.
Graftless techniques are the new frontier. Studies are ongoing, and the techniques may develop and become standardized as fast as their predecessors in endothelial keratoplasty. However, I foresee that, for a number of years at least, their use will be limited to cases of Fuchs’ dystrophy, in which the endothelium can still respond to stimulation. At the stage of bullous keratopathy and in cases in which the endothelium is completely destroyed, for example, by trauma, previous surgery, silicone oil or some other kind of aggression, a graft will still be needed.
Descemetorhexis-only was described by Gerrit Melles some years ago, and then some isolated cases were published worldwide. It has proved successful in a subgroup of Fuchs’ patients, in whom the extraction of the Descemet has allowed repopulation of healthy cells. Could it also work in trauma cases? We do not know yet, but up to now stripping alone has never been successful in pseudophakic bullous keratopathy.
I have never tried this approach intentionally, but it happened that I tested it unintentionally in two cases in which I was unable to obtain a well-attached DMEK graft. In both cases the cornea eventually cleared over a period of about 4 to 8 months. I am not so sure, however, that the same effect could be achieved by stripping alone without the presence of a graft. Some of the cases in which Melles injected a free-floating Descemet roll were aphakic bullous keratopathy, and I do not think that the technique would work in bullous keratopathy without any additional cells being injected.
Kinoshita’s technique of cultured cell injection is a fascinating project to which I am planning to contribute in the near future. My views on it today are based on Kinoshita’s data and on common sense. It makes sense that this technique will work, thus leading to easier, reproducible and low-cost management of Fuchs’ dystrophy.
Today’s management of Fuchs’ patients is close to the results of refractive surgery. Within 2 or 3 weeks, patients can be in the 20/25 to 20/20 range, postoperative problems are generally quite rare, and rejection rate is low, in fact much lower than with DSAEK. Results are truly fantastic, and the future holds even greater promise.
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- José L. Güell, MD, OSN Europe Edition Board Member, is director of the Cornea and Refractive Surgery Unit at the Instituto de Microcirugia Ocular, Barcelona, Spain, and an associate professor of ophthalmology at the Universitat Autónoma de Barcelona. He can be reached at guell@imo.es.
Disclosure: Güell reports he is a consultant for Alcon and Carl Zeiss Meditec.