EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/511377
EW CORNEA 38 May 2015 by Maxine Lipner EyeWorld Senior Contributing Writer Standardized DMEK approach garners results apply an S-shaped stamp to the De- scemet's membrane non-endothelial side so that we can easily confirm orientation of the tissue at the time of surgery," he explained, adding that the traditional method of deter- mining which side is up by looking at how this very thin graft naturally scrolls is not that reliable. "Some- times it doesn't scroll how you expect it to," Dr. Straiko said. "We think one of the leading causes of primary graft failure is upside-down grafts." One of the other major mod- ifications was changing the graft injector. Dr. Straiko finds that many physicians are using modified intr - ocular lens cartridges. "The prob- lem is that these injectors are not designed to handle biologic tissue and have not been validated for that use. The materials may not be bio- compatible with the endothelium. They are [made of] plastic, which sometimes the graft may adhere to," Dr. Straiko said. He added that this could cause damage to the delicate tissue. Also, sometimes issues with chamber collapse while using these makeshift systems can occur, leading to injection problems and damage to the graft. With this in mind, he developed a new system, dubbed the Straiko injector, specifically for DMEK. At the heart of this is a modified Jones tube. "The Jones tube is FDA approved for lacrimal surgery, but we're using it for corneal surgery and attaching it to a syringe of balanced salt solution," Dr. Straiko said. He also reported that vital dye staining studies indicate very little tissue damage with this system. Another area identified as problematic was the graft unfolding technique. To help make this step safer and easier, Dr. Straiko advo- cated switching to a no-touch tap technique. This involves indirectly opening the graft by tapping and stroking the cornea and sometimes using a small air bubble to generate fluid currents in the anterior cha - ber, he explained. "The graft is so fine that it doesn't take much manipulation— those minute currents can have quite an impact," he said. Also, as others have recom- mended, Dr. Straiko is careful to avoid overlap of the graft with the host Descemet's membrane. "That seems to help the graft to adhere better and makes it much less likely to have an edge lift or a rebubble," he said. A dvances in endothelial keratoplas- ty have occurred at a rapid rate considering that a decade ago corneal specialists were still performing penetrating keratoplasty for all endothelial replacement. The latest innovation in en- dothelial surgery is Descemet's membrane endothelial keratoplasty (DMEK). This technique eliminates the stromal carrier used in Descemet's stripping automated endothelial keratoplasty (DSAEK) and has been reported to result in better vision and less graft rejection. However, the DMEK procedure has been slow to be adopted by many corneal surgeons due to the higher complication rate and steep learning curve. Complications reported after DMEK surgery include increased early endothelial cell loss, increased graft detachments with greater rates of rebubbling, and loss of donor tissue in the preparation of the graft. In addition, the tissue is more difficult to handle once in the anterior chamber, resulting in longer surgical time. This month's "Cornea editor's corner of the world" focuses on how DMEK as a technique can be standardized to potentially lower complications so that more surgeons may feel confident with its learning cu ve. Michael Straiko, MD, discusses his experi- ence with DMEK, what steps are important to standardize the surgery, and pearls to decrease complications. Clara C. Chan, MD, FRCSC, FACS, cornea editor Cornea editor's corner of the world Straiko injector with DMEK graft Source: Michael D. Straiko, MD Looks to broaden appeal A new standardized version of Descemet's membrane endothelial keratoplasty (DMEK) might make it possible for more prac- titioners to attain success with the transplant procedure, according to Michael D. Straiko, MD, associate director of corneal services, Devers Eye Institute, Portland. This more consistent approach lowers compli- cations and allows for fewer graft detachments, he said. In developing this approach, Dr. Straiko wanted to standardize the technique so that as many surgeons as possible could apply his tech- nique to the DMEK procedure. "When the new technique came out, the problem with DMEK was that the complication rate was too high—there were too many rebub- bles and too many graft failures," Dr. Straiko said. "A lot of this is the learning curve of getting used to a very new procedure." He viewed this steep learning curve as substantially curtailing adoption of the DMEK approach. "Before something can be mass adopted, we have to make sure that the outcomes are good and the risks are minimized as much as possible," Dr. Straiko said. "That's the goal of the technique I've been developing, to come up with something that can be done by many different surgeons and not just experts at individual centers." As a result, he hopes that this can reach more patients. Eyeing modification The standardized approach has a variety of modifications. o begin with, the use of pre-stripped tissue is recommended, Dr. Straiko not- ed. "That way it can be prepared at an eye bank and they can do post-preparation validation," he said. "After they prepare the tissue, they can examine it again and make sure that it meets EBAA [Eye Bank Association of America] require- ments." Dr. Straiko prefers that eye banks S-stamp the tissue to make the correct orientation clear. "They