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69 January 2015 EW MEETING REPORTER completed, even if the bubble does burst into the anterior chamber. DALK pearls When performing DALK, Luigi Fontana, MD, Reggio Emilia, Italy, said that the needle "is dangerous"— the sharp point can easily perforate the Descemet's membrane. He there- fore recommends instead using any of the DALK big bubble technique cannulas currently available. All have blunt tips and bottom-oriented ports that inject air down onto the membrane surface. In addition, Dr. Fontana offered the following pearls: 1.Insert the cannula slowly into the stroma, stopping when resistance is suddenly lost. This is where you should begin injecting air to create the bubble. If you do not feel this loss of resistance, withdraw and be- gin again from another direction. 2. Bubble enhancement: If the bub- ble you are creating stops enlarging, stop injecting air. Leave the cannula in place. Create a paracentesis to release some aqueous fluid from the anterior chamber. This will decrease the anterior chamber pressure and should allow the bubble to expand. 3. Stroma debulking: If the stroma is under 400 µm, there is no need to debulk the stroma. Debulk the stroma when it is over 400 µm. 4. Small bubble test: Inject air bub- bles into the anterior chamber. If they remain in the periphery when you move the eye around, you have created a big bubble and may proceed with surgery. 5. The "safe" slash: Convert a "brave" slash to a "safe" one by decompressing the anterior chamber first. Create a paracentesis to allow some aqueous fluid to escape before slashing open the bubble. The re- duced anterior chamber pressure will keep the posterior surface of the big bubble away from your instruments. 6. Manual dissection: If you are not able to create a big bubble, you can perform a manual dissection. Make a vertical cut right into the remaining stroma. You can recognize the po- sition of the Descemet's membrane by a difference in color between the light reflected by the stroma and the iris reflex coming from behind the cornea. Insert a blunt dissector and dissect deep into the stroma just before the Descemet's membrane. Data raises DALK questions In a symposium on anterior lamellar keratoplasty techniques, Bennie H. Jeng, MD, Baltimore, shifted gears by focusing on current published data—and raising questions about DALK. "I think it's important for us to take a step back and review the evidence, what it tells us about the outcomes of DALK versus PK [pene- trating keratoplasty]," he said. When Dr. Jeng was first learning to perform DALK about 10 years ago, he said that he and his colleagues were struggling not only with how to perform it successfully, but also with whether it was worthwhile doing it and if it was "worth all the extra effort." Looking at the literature that was available at the time, the rate of successfully creating a big bubble and baring Descemet's membrane was only in 37% to 64% of cases, depending on the case series. And yet, Dr. Jeng said, surgeons at the time were still able to com- plete 91% to 96% of DALK. At the time, the major advan- tage that was evident from data was that the endothelial cell count loss was "very, very low" with DALK; however, even then it was well known that stromal rejection was a very real entity that had to be dealt with. In terms of visual acuity out- comes, what was significant was that while 97% of cases achieved VAs of 20/50 or better when the Descemet's membrane was successfully bared, only 67% of cases achieved good visual outcomes when the Descem- et's membrane was not successfully bared. From 1997 to 2009, there were only 11 studies comparing DALK and PK, none of them providing level I evidence; only one was level II, and the rest were level III. Nevertheless, nearly 1,000 eyes were compared, almost 500 in each group. "What they found was that DALK was equivalent to PK for best spectacle-corrected visual acuity es- pecially if there was normal stroma left," Dr. Jeng said. "At that time, improved graft survival could not yet be officially demonstrated, but the postoperative data indicating that the endothelial cell density was superior in DALK was convincing and encouraging. "Their conclusion was that DALK has important theoretical advantages that we're well aware off," he added. Nonetheless, DALK is a longer procedure, so Dr. Jeng continued to wonder, is it really worthwhile? Is it cost-effective to do it? Cost-effectiveness studies suggest that while DALK is initially more expensive, the incremental cost-utility ratio is actually more favorable if you extend the compu- tation over 20 years, into the long- term postoperative period, factoring in graft longevity—at the time projected to be 49 years for DALK, 17 years for PK. Despite all this positive evi- dence, in a later study in patients who had PK in one eye and DALK in the other, while intraoperative and postoperative outcomes were sim- ilar, 8 out of 10 patients preferred their PK eyes for vision and overall satisfaction. Which leads to the Australian Corneal Graft Registry study con- ducted by Douglas J. Coster, MD, Adelaide, Australia, and colleagues. Some ophthalmologists question registries as sources of research data. Data collection, after all, could not be expected to be as rigorous as in a formal study. However, Dr. Jeng said, "when we look at registries, these are real world experiences." Comparing himself to other surgeons such as Mark A. Terry, MD, Portland, and Francis W. Price Jr., MD, Indianapolis, Dr. Jeng said he had 2 things against him: his "inferior" surgical skills and his patient population. "I don't think my outcomes will ever be as good," he said. "Registries give us that overview of a worldwide perspective of everybody doing a certain procedure." The Australian registry covers 17 years with more than 17,000 grafts. Based on the registry data, with the population stratified and looking into keratoconus patients alone, graft survival and visual acuity were actually better with PK than DALK. "DALK definitely has theoreti- cal advantages," Dr. Jeng said. "But the evidence continues to evolve. We have lots of data to suggest that DALK is better in terms of less endo- thelial rejection, it has comparable vision to PK, potentially longer graft survival in some studies, potentially cost effectiveness, but the recent data, looking at the real world, may suggest otherwise. "It is up to each of us to interpret for our own patients the way that we want to [perform keratoplasty]," he added. EW T he Asia Cornea Society (ACS) launched into its 4th Biennial Scientific Meeting (2014 ACS) accompanied by the propulsive beats of the Ten Drum Percussion Art Group. The strength of the group's beating drums represents the "enduring vitality and radiant energy" of the meeting's host country, Taiwan. In her welcome address at the meeting's opening ceremony, Fung- Rong Hu, MD, president, 2014 ACS, and president, Ophthalmological Society of Taiwan (TOS), said she hoped the meeting "would provide a platform for the exchange of knowl- edge and for the enhancement of vital skills in the rapidly advancing field of cornea." "We hope to foster greater un- derstanding and promote advance- ments in the diagnosis and manage- ment of corneal diseases," she said. Dr. Hu thanked the meeting's international partners: the Cornea Society, the American Academy of Ophthalmology (AAO), the Interna- 2014 ACS launched to the sound of drums by Chiles Samaniego EyeWorld Senior Staff Writer EyeWorld Daily eNews • The official 2014 ACS Taipei Daily Sunday November 16, 2014 digital.eyeworld.org tional Society of Refractive Surgery (ISRS), the Association of Eye Banks of Asia (AEBA), and SightLife—de- scribed on their website as "the only non-profit global health organi- zation focused solely on eliminat- ing corneal blindness around the world." Apart from participating in the scientific sessions, Dr. Hu encour- aged attendees to take time to enjoy "the rich Chinese culture and hospitality" of Taiwan, a country she said is "full of cultural, natural, and hi-tech wonders." ACS Vice President Shigeru Kinoshita, MD, Kyoto, Japan— speaking for ACS President Donald Tan, MD, Singapore, who could not be present at the meeting due to a family emergency—also welcomed attendees. He extended the ACS Council's "immense appreciation" for Dr. Hu for her "superb support and cooperation" to make the meet- ing possible. In addition to allowing important academic exchange, he said that the ACS biennial meeting was established to "promote mutual friendship among Asian corneal spe- cialists and the younger generation of ophthalmologists, researchers, and co-workers." "We feel very fortunate that many of the most distinguished ophthalmologists and scientists in the cornea field worldwide are gathering here in Taipei," he said. "This meeting comes at a point in time when cutting edge advance- ments are being made in the field of ophthalmology and visual science. The state-of-the-art developments are greatly impacting the treatment of corneal diseases. "This meeting succinctly encap- sulates our aim of zooming in on the newly emerging advancements in surgical and laser technologies as well as translational and clinical re- search," he added. "This meeting is guaranteed to promote an enormous amount of international scientific exchange." At the time of the opening cer- emony, the ACS had counted over 600 participants from all over the world in attendance. The ACS also honored its most distinguished members and partners at the opening ceremony. Fung-Rong Hu, MD continued on page 3 Asia Cornea Society Daily now online at: daily.EyeWorld.org Read the latest news from the Asia Cornea Society 4th Scientific Meeting held in Taipei, Taiwan, with pages of photos from the key events.

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