EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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E W FEATURE 64 Dr. Baig said it's difficult to pin- point specific advances needed be- cause many surgeons have diverse reasons for not performing DALK. "Commonly cited aversions to DALK are the increased procedure time, perceived technical difficulty, and having to convert to PK if Descemet's membrane is violated," he said. However, Dr. Baig noted that procedure time for DALK has decreased, possibly due to advances in instrumentation. Pearls for beginners Corneal transplant surgeons should look at DALK for patients with stro- mal disease with a normal endothe- lium, Dr. Holland said. They should also obtain instruments specific to DALK as part of that transition, he s aid. Dr. Holland said that taking courses at major meetings and watching surgical videos could help those surgeons beginning with DALK. He said that there could be a number of problems for beginning DALK surgeons and suggested practicing DALK on any patient u ndergoing a PK in order to become familiar with the procedure. "The beauty is, the worst outcome on a problematic DALK is you're going to do a PK," Dr. Holland said. "One key to starting out with DALK surgery is to talk to surgeons who have performed DALK," Dr. Garg said. "Talking through the procedure can often help in the learning curve." "Another key point is to not get discouraged if Descemet's membrane is perforated—it is bound to happen," Dr. Garg said. Dr. Lee likes to take two chances to create the big bubble using Dr. Anwar's technique. "A trephination down to 300 microns helps with appropriate depth prior to needle or cannula insertion," he said. "If the big bubble is unsuccessful, the ante- rior stromal removal step can be per- formed at this point to remove the anterior half of stroma and a repeat needle or cannula insertion into the posterior stroma gives you a second chance for the big bubble creation." He also recommended using a blob of viscoelastic over the central stroma after the big bubble has been created. Getting better tissue apposi- tion with interrupted sutures versus a running suture technique is also useful, he said, because the latter increases the risk of tissue override. "As always, book yourself lots of time," Dr. Baig said. "Start with an easier case, with enough stroma in the center and the periphery." Hav- ing preoperative pachymetry maps and appropriate DALK instrumenta- tion are also important, he said. The role of the f emtosecond laser Dr. Garg said that he currently uses the femtosecond laser routinely in DALK surgeries. "As many of my transplants are performed with the femtosecond laser, I know the approximate depth of my incision," he said. H e added that it is customary to leave a 70 µm bridge posteriorly, and this depth means that the needle placement is very near Descemet's membrane. "If I am unsuccessful, I can easily convert to a full thickness keratoplasty," he said. Dr. Baig also sees the benefit of the femtosecond laser for this proce- d ure. "The femtosecond laser can produce incisions to an accurate depth, thus reducing the risk of per- foration at this stage of the proce- dure," Dr. Baig said. "Moreover, the femtosecond laser can produce graft and host junctions that are identi- cally matched and complex in shape, including the zigzag, top hat, and mushroom incision morpholo- gies." "I think femtosecond laser ap- plication can increase efficiency of manual DALK," Dr. Lee said. "If we are able to direct the femtosecond laser to create a tunnel into the deep stroma, affording an easier cannula pass into the stroma for big bubble creation, it may increase efficiency of Anwar's technique as well." He added that the major hurdle for using the femtosecond laser is that it adds extra expense for both the sur- geon and patient. Dr. Holland thinks that the fem- tosecond laser can benefit all types of lamellar procedures, but he also stressed the need to overcome the cost obstacle of the femtosecond laser technology. "It's possible that the femtosec- ond can eventually be programmed to make that deep cut if we could avoid damaging underlying endothelium," he said. He also noted obtaining the big bubble could potentially be made easier with this technology. EW Editors' note: Dr. Garg has financial interests with Abbott Medical Optics (Santa Ana, Calif.). Drs. Holland, Lee, Baig, and Shamie have no financial interests related to this article. Contact information Baig: baig247@gmail.com Garg: gargs@uci.edu Holland: eholland@holprovision.com Lee: wblee@mac.com Shamie: nshamie@yahoo.com February 2011 Corneal infections February 2014 Advances continued from page 62 Immediate postop eye after DALK S ource (all): W. Barry Lee, MD 56-68 Feature_EW February 2014-DL2_Layout 1 1/30/14 10:44 AM Page 64