FEB 2014

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

Issue link: https://digital.eyeworld.org/i/274531

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Page 63 of 114

E W FEATURE 6 1 upside down graft placement. New graft unfolding techniques such as the tap technique, first reported by Yoeruek, have greatly simplified un- folding and positioning the graft." In addition, 20% SF6 has helped him achieve higher success rates, with his group's rebubble rate below 6%. "All of these factors are coming together to make DMEK ready for prime time. I suspect some surgeons may be waiting for longer-term cell density data prior to proceeding," Dr. Straiko said. Novel advancements for graft preparation include the submerged hydro-separation technique that Mohit Parekh, MD, shared at the Cornea Society/Eye Bank Association of America's 2013 Fall Educational Symposium in New Orleans, Dr. Straiko said, and the Muraine tech- nique, which requires equipment from Moria (Antony, France). Pearls for beginning surgeons The first pearl for the beginner DMEK surgeon, Dr. Shamie said, is to use pre-stripped tissue from an eye bank. "To attempt to prepare your own tissue when you're beginning is too risky," she said, unless "you can practice on the donor grafts used when performing DALK. The second pearl is, in graft adhesion, strip the recipient Descemet's larger than the size of the graft that is being inserted into the eye, she said. "I have found … that the DMEK graft sticks better to bare stroma than it does to overlapping areas of Descemet's; Descemet's doesn't stick to Descemet's well. It's different than DSAEK. With DSAEK, you want t o strip the recipient stromal bed smaller than the size of the donor graft to avoid having bare areas of the stroma without endothelium resulting in peripheral bullae. But in DMEK, if you're putting in an 8 mm graft, you want to strip at least an 8.5 mm area of the recipient stroma," she said. T he third pearl is that the ability to shallow the chamber is critical when trying to open the scrolled donor DMEK tissue. "[Being] able to shallow the chamber and to use the iris as a cushion during the step when the surgeon tries to open the scrolled graft is critical," Dr. Shamie said. " Because of that, you need to have a miotic pupil and a flat or shallow chamber. With that in mind, a pa- tient with a deep anterior chamber or one who is post-vitrectomy, where shallowing of the chamber will be difficult will pose a lot of challenges that a beginning DMEK surgeon might not want to tackle." In addition, the graft will scroll away from the endothelium, making it difficult to determine which side is facing up. She recommends using trypan blue to stain the graft and watching for the graft edge to scroll up "like a basket," which determines that the endothelium is facing down. Intraoperative use of a slit beam may help as would a graft stamped with an S. Another pearl is to use topical instead of general anesthesia, Dr. Price said. This can assist when the eye is filled with air or fluid, as pa- tients can then respond that they still see light and do not have a vascular occlusion. Patient selection is important, too. Select eyes that are between 11.5 mm and 12 mm and that are standard with no confounding issues. "It is critically important to se- lect your DMEK patients carefully," Dr. Straiko said. "I recommend DMEK only in patients with a stable bicameral eye. Avoid patients with tubes, trabs, iris defects, aphakia, or post-vitrectomy eyes." Understanding that there will be a learning curve is key for the begin- ner surgeon, Dr. Price said. He likened it to when surgeons made the switch from extracapsular cataract surgery to phacoemulsifica- tion. " Like phaco, surgeons are going to have to spend a lot of time to learn the technique," he said. "Most people will not be able to get by just doing two cases a month. They're going to need to do multiple cases to get the skill set and the pattern recognition to actually do it well." Pitfalls for beginning surgeon The biggest pitfalls of DMEK would be the higher rebubble rate com- pared to DSAEK, as well as the higher risk of returning to the oper- a ting room, according to Dr. Shamie. "I tend to watch my DMEK patients more closely," she said. "I see them several times in the first month, and if the edges are not 100% attached, there's a lot of wait- ing and watching and making sure that there's no extension of that sep- aration. Taking advantage of an anterior segment OCT is helpful in monitoring the graft adhesion in the critical early postoperative period." Dr. Straiko said it is vital that surgeons not think of DMEK as a variation of DSAEK. The two surger- ies are different, with different skill sets. "Stripping the host is the only similarity," he said. "It is important to practice your technique on donor globes prior to attempting it on your patients. It is also important to find a mentor or take a course and learn from other people's mistakes—it will shorten your own learning curve." Both Drs. Price and Straiko ad- vised beginner surgeons not be dis- couraged by early DMEK experience. "You can't get frustrated if you have difficulties," Dr. Price said. "You have to practice. You need to use a step-by-step technique to get started. Plan to do a series of cases. Book about two hours for the first few cases so that you're not running over in the operating room. No- body's going to complain if you get done early. Just take your time, and it should go well." EW Editors' note: Drs. Price, Shamie, and Straiko have no financial interests related to this article. Contact information Price: francisprice@pricevisiongroup.net Shamie: nshamie@yahoo.com Straiko: mike.straiko@gmail.com February 2011 I n t r a o p D M E K p r o c e d u r e S o u r c e : M i c h a e l S t r a i k o , M D At three weeks postop, the case has a clear cornea after DMEK for Fuchs,' with a small peripheral iridotomy present. Source: Michael Straiko, MD February 2014 Corneal infections 56-68 Feature_EW February 2014-DL2_Layout 1 1/30/14 10:44 AM Page 61

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