EyeWorld Asia-Pacific September 2011 Issue

48 EW CORNEA September 2011 microns or so,” he said. Then he uses a blunt lamellar instrument to try to dissect a tunnel from the periphery more centrally. He can then place the air cannula into this. “I think that the surgeon should abandon needles as injectors and get one of the designer cannulas,” he said. “These are curved cannulas that direct the air posteriorly.” When the air is injected, this separates Descemet’s from the overlaying stroma. From there practitioners need to use a super sharp blade to let the air out of the bubble. Then Descemet’s membrane comes forward. “I then convert over to the viscoelastic dissection to slowly inject the viscoelastic of my choice, which in this case would be Healon [Abbott Medical Optics, Santa Ana, Calif., USA] into that Descemet’s space,” Dr. Holland said. “I then use blunt scissors to remove the overlaying stroma.” If you don’t get a big bubble on the first attempt, Dr. Holland recommended doing some lamellar dissection. “Take off the anterior 50% of the stroma, and then repeat the big bubble attempt with the same technique as was tried before,” he said. He finds that the combination of the deep lamellar dissection, the tunneling with the lamellar dissector, and the use of the specialized air cannulas has made this operation a very successful procedure. Making the transition For those who are aiming to make the transition, Dr. Verdier recommended going to national or international meetings where he finds there are usually good presentations by leaders in the field. He also suggested watching videos and reading articles. “In some of the major journal articles there are video links,” Dr. Verdier said. Similarly, Dr. Holland recommended reading textbooks and watching videos. He also suggested attempting the DALK approach on every patient who’s undergoing a keratoplasty procedure for stromal disease who has a normal endothelium. “Approach them as a DALK procedure,” he said. “The worst thing that will happen is that you’ll do a PK.” He stressed that this is far better than acquiescing and continuing to rely solely on PK. “If a surgeon says that he or she has good results with PK for stromal disease, that surgeon is in denial because the results are not as good as the long-term results of DALK,” he said. In his view the worst that will happen is that practitioners will have to convert to PK. “There’s nothing to lose as a surgeon and there’s a lot to gain for the patient,” Dr. Holland said. Going forward, Dr. Holland thinks that the next generation of DALK dissection is probably going to involve the femtosecond laser. “Not only will we dissect down with the femtosecond, but we’ll also use it to make the other incisions in the cornea, so that the trephinations will be replaced by the femtosecond laser and the stromal dissection,” he said. “We may do a combination using the big bubble if the femtosecond laser can’t do as clean a job as air injection now.” But Dr. Holland thinks that as is becoming the case in cataract surgery, practitioners will ultimately become more comfortable with the idea of using the femtosecond laser in cornea surgery. EW Editors’ note: The physicians mentioned have no financial interests related to their comments. Contact information Florakis: 212-305-3378, gjf2@columbia.edu Holland: 859-331-9000, eholland@holvision. Com Verdier: 616-949-2001, daverdier@aol.com that the endothelial cell loss with DALK is much less. “We know that the cell loss is somewhere between 10–15% after 2 years, but then it seems to settle down to what the normal cell loss or near what the normal cell loss is in an un- operated cornea,” Dr. Verdier said. “Preliminary data is very positive suggesting that the endothelial cell loss will be dramatically less in DALK.” Also, with DALK, concerns about graft rejection are vastly reduced. “The rejection of the great majority of corneal grafts are endothelial and we take that totally out of the picture by retaining the patient’s own endothelium,” Dr. Verdier said. “So the biggest problem with corneal transplant failure historically in PK is rejection and even without rejection, late endothelial failure, which is also a significant issue.” The third issue plaguing PK is surface disease. While DALK does nothing to alleviate this, Dr. Verdier still sees it as an improved procedure, which has eliminated two of the three big problems associated with PK. While there is no long-term data on this yet, the evidence suggests DALK will only need to be done once. “I think that almost all of us feel that if you can pull it off and complete the procedure well, the transplant is very likely to last the patient’s lifetime,” Dr. Verdier said. He sees this as important for several reasons. “You increase your chance of rejection when you go back for a second or a third procedure,” he said. In addition, rehabilitation after corneal transplantation can be much more taxing than other commonly performed visual procedures. “Cataract patients see better within weeks, and PK patients see better within a year or two. It’s a long period of not seeing very well.” Additionally, in about 1% of cases, PK patients run the risk of having an expulsive hemorrhage. “That’s a devastating event,” Dr. Verdier said. “People lose their vision permanently from one of those. The risk of this is pretty much eliminated when Descemet’s membrane is preserved.” “The other problem with PK is that at some point in their life, about 5% of our PK patients end up with a ruptured globe through trauma,” Dr. Verdier said. “This is usually inadvertent.” Unfortunately, he finds that at least half of those people never see well afterward. On the other hand, with DALK he feels that there is less chance of this occurring. “It looks like even though the only thing that we’re preserving in DALK is the endothelium and Dedcemet’s, which is about 1% of the cornea, that membrane is tough enough to be a barrier to trauma,” he said. All of this considered, Dr. Verdier pointed out that there is much to gain and little to lose by attempting a DALK procedure. “I know that if it was my own family member or me, I would rather have the DALK done,” he said. If you fail with the DALK you can always convert to a PK right there on the table. “There’s no extra morbidity or loss of outcome for the patient. It’s as if you did the PK in the first place,” Dr. Verdier said. Performing DALK Dr. Holland has already made the switch to DALK. For the procedure, he likes the big bubble technique. “In my hands it has worked the best,” he said. While there are different ways to do this, he has a couple of tricks that he finds helpful. “I trephine down to about 90%,” Dr. Holland said. “Then what I think is really important is to get a deep dissection to pre-Descemet’s.” He starts out with a super sharp blade and then extends his trephination a bit anteriorly to get as deep as he can and as close to Descemet’s as possible. “I’m usually within 50 Talking from page 47