EyeWorld Asia-Pacific September 2011 Issue

46 EW CORNEA September 2011 The eye at the left is one that underwent PK at the 7-year post-op mark; at the right, the same patient’s DALK eye at just 18 months post-op, which appears almost identical Source: David D. Verdier, MD Talking DALK for stromal disease by Maxine Lipner Senior EyeWorld Contributing Editor DALK procedure gaining popularity around the world, making inroads in the US F or many years full- thickness penetrating keratoplasty (PK) has been the primary option for patients with severe stromal disease. However, deep anterior lamellar keratoplasty (DALK) has been coming on strong, particularly in countries outside of the United States, according to David D. Verdier, MD, Verdier Eye Center, Grand Rapids, Mich., USA. “We are behind much of the rest of the world when it comes to DALK,” Dr. Verdier said. “In Europe, the Middle East, and Singapore, DALK is performed much more frequently.” Dr. Verdier points to Eye Bank Association of America data, which in 2009 put anterior lamellar procedures at just 2% of transplants performed in the US, compared with 55% for PK and 43% for endothelial keratoplasty. What’s holding practitioners back? Edward J. Holland, MD, professor of ophthalmology, University of Cincinnati, Ohio, USA, and director, cornea service, Cincinnati Eye Institute, thinks that from the start, those in other parts of the world were more attuned to the procedure. “The interest started in the Middle East, in Europe, and in Asia,” he said. “While we were always interested in doing DALK for stromal disease, the problem was interface haze, so we basically abandoned it. But other parts of the world kept trying to perfect the procedure, mostly out of necessity.” Now the DALK technique is beginning to offer up real dividends. “I think that the techniques of the big bubble, Anwar’s, and others that allow us to get a good dissection down to Descemet’s make this procedure for stromal disease far superior to what we can do with penetrating keratoplasty,” Dr. Holland said. “However, US surgeons have been complacent for the most part. This has a steep learning curve, it is a difficult operation to master, and it takes more time than PK.” In addition, many surgeons have become wedded to familiar PK. “They say, ‘I do a very good PK, this is what I’ve been doing for the last 20 years, why should I change?’” Dr. Holland said. George J. Florakis, MD, clinical professor of ophthalmology, Columbia University, New York, NY, USA, sees a host of things holding practitioners back from embracing DALK. He pointed out there is already the PK procedure for corneal transplantation, which works very well. “Many of us have done it for many years and do it well,” Dr. Florakis said. “At least in some studies, it offers better visual acuity with a full-thickness corneal transplant than DALK.” There are, of course, other studies that show the opposite to be true. Also, practitioners have become very skilled at PK. “Because we’ve been doing it for such a long time, we’re good at it,” he said. “It’s not a very good reason, but the practicality is we’re in our comfort zone with PK.” DALK is also technically difficult to master. “Sadeer Hannush [MD, attending surgeon, Cornea Service] at Wills Eye Hospital [Philadelphia, Pa., USA] once said that this is the toughest new operation that he had to learn since fellowship, about 20–25 years ago,” Dr. Florakis said. “It’s technically difficult with a fairly high conversion rate.” He pointed out that many who attempt a DALK ultimately end up converting to a full-thickness transplant anyway. During a recent meeting of the Northeast Cornea Society, which Dr. Florakis attended, 14 prominent cornea surgeons were informally polled. The conversion rate there was found to be from 30 to 50%, depending upon where they were in the learning curve. In addition, some of the potential benefits of DALK remain unstudied. “Many of the DALK advantages are theoretical; they haven’t been proven with statistics or papers,” Dr. Florakis said. “But they are probably real.” For example, he points to people saying there’s no endothelial rejection with DALK because no endothelium is being replaced. Even without study this makes sense. Dr. Florakis noted that another sticking point might be that the DALK procedure has not quite come into its own yet. “It may be a great procedure, and maybe it’s still in the development stage,” he said. “When it becomes more developed and perhaps new instruments emerge or something changes about it, more people will feel comfortable doing it.” He thinks perhaps some practitioners are wearied by the idea of having to master yet another technique. “We just got over learning endothelial keratoplasty,” Dr. Florakis said. “That took a lot AT A GLANCE • In the US in 2009, only 2% of corneal transplants were done using an anterior lamellar approach • Much of the rest of the world has already adopted the DALK procedure • Some US surgeons are deterred by the fact that DALK is a technically difficult procedure with a steep learning curve • Many surgeons remain entrenched and are reluctant to leave their comfort zone of performing PK • With DALK, key concerns about graft rejection and late endothelial failure are vastly reduced • The DALK procedure is likely to last the patient’s lifetime • The worst thing that will hap pen with a failed DALK is that it will be converted to a traditional PK