FEB 2014

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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E W FEATURE 62 by Ellen Stodola EyeWorld Staff Writer Advances in DALK DALK has become more popular with advances, but some are still hesitant to adopt it D eep anterior lamellar keratoplasty (DALK) has become more popular among surgeons, aided by advances in instrumenta- tion and the benefits that it offers. However, many surgeons still have not adopted this technique. Neda Shamie, MD, associate professor of ophthalmology, Doheny Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, and medical d irector, Doheny Center Beverly Hills; Sumit (Sam) Garg, MD, vice chair of clinical ophthalmology, medical director, director of technology, and assistant professor of cataract, corneal and refractive surgery, Gavin Herbert Eye Institute, University of California, Irvine; W. Barry Lee, MD, Eye Consultants of A tlanta, Piedmont Hospital, and medical director of the Georgia Eye Bank, Atlanta; Kashif Baig, MD, assistant professor, University of Ottawa; and Edward J. Holland, MD, director of the cornea service, Cincinnati Eye Institute, and profes- sor of ophthalmology, University of Cincinnati, spoke about advances in D ALK and advice for those begin- ning to use it. Advances in instrumentation for tissue preparation "One of the greatest advances in DALK surgery was the advent of the 'big bubble technique' first described by Dr. Mohammed Anwar," Dr. Baig said. A number of other ophthalmol- ogists have also designed instrumen- tation to aid in DALK surgery, he said. "Each group of instruments aims to specifically address the aspects of DALK surgery where complications may arise or where challenges may be overcome via purposefully designed instruments." Dr. Baig said that most DALK sets include some sort of dissector, helpful for creation of the big bubble. Cannulas are also used for c reation of the big bubble, most with the port on the bottom aspect of the instrument. A variety of spat- ulas and scissors specific to DALK are important once the big bubble is cre- ated to reduce the risk of rupture of Descemet's membrane. Before some of the newer tech- niques, Dr. Holland said there was a b elief that vision was not as good with DALK, but this is no longer true with the use of the big bubble technique. "A lot of surgeons under- stand the big bubble technique, in which we inject air into the deep stromal membrane to separate Descemet's from the overlying stroma, and once you achieve a b ig bubble, the ability to separate stroma and achieve successful DALK is pretty good," he said. The popularization of DALK has come with many advances in instrumentation, Dr. Garg said. "I currently use the Fogla DALK in- struments, which I find work quite well," he said. "With any of these instruments, the key is to be gentle with Descemet's membrane." For this reason, he said that many of the instruments have blunted edges to decrease the chance of perforation. "We now have a number of cannulas available from various instrument companies that allow a tunnel creation deep into the corneal stroma, lessening the risk of corneal perforation with a sharp needle," Dr. Lee said. "Instruments to facilitate ease of stromal removal have also increased the success of D ALK techniques." Some of the specific instruments that aid in this include dull lamellar blades and scissors with dull edges. Additional advances needed for DALK Dr. Lee believes that advances for D ALK are in place and surgeons need to realize the advantages of learning this technique over pene- trating keratoplasty (PK). "A number of corneal surgeons still feel there are no advantages of DALK over PK, and this is just not the case," he said. "The 0% risk of endothelial rejection and increased risk of m aintaining a DALK graft over your lifetime compared to failure of a PK can not be emphasized enough." A large challenge associated with DALK surgery is the rate of Descemet's membrane perforation, Dr. Garg said. "If the rate of perfora- tion could reliably be minimized, I'm sure that more surgeons would adopt the technique." Intraoperative imaging could help in this regard. Dr. Shamie mentioned that, as with any paradigm shift, there need to be changes before DALK is recog- nized as a standard approach. "The knowledge about the lower rejection rates, more prolonged life of the corneal transplant, lower depend- ency on steroids, and more rapid recuperation of vision by removing sutures sooner with DALK needs to be emphasized," she said. February 2011 Corneal infections February 2014 Bare Descemet's membrane after stromal removal AT A GLANCE • The creation of the big bubble technique was one of the biggest advancements in DALK surgery. W ith this, air is injected into the deep stromal membrane to separate Descemet's from the overlying stroma. • Instruments with blunted or dull edges help to decrease the chance of perforating Descemet's membrane in DALK. • The femtosecond laser could prove helpful for cuts in DALK, but cost obstacles need to be addressed before it can be utilized. continued on page 64 Stromal removal during DALK procedure 56-68 Feature_EW February 2014-DL2_Layout 1 1/30/14 10:44 AM Page 62

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