EyeWorld India March 2018 Issue

March 2018 24 EWAP FEATURE Surgical pearls for DMEK by Ellen Stodola EyeWorld Senior Staff Writer AT A GLANCE • Surgeons suggested using slightly different sizes for donors and recipients when determining graft size. • Using pre-marked tissue with an S-stamp can help surgeons ensure correct orientation of the DMEK tissue. • It may be best to avoid using DMEK in some patients. Patients with prior glaucoma surgery or vitrectomy may be better suited for DSAEK. Surgeons discuss their approach to DMEK to help improve outcomes W hen performing Descemet’s mem- brane endothelial keratoplasty (DMEK), there are a number of details for surgeons to pay attention to for a successful surgery. Leejee H. Suh, MD , associate professor of clini- cal ophthalmology and director of the Laser Vision Correction Center, Edward S. Harkness Eye Institute, Columbia University, New York, W. Barry Lee, MD , Eye Consultants of Atlanta, and Peter Veldman, MD , assistant professor, residency program direc- tor, and vice chair f o r education, Department of Ophthalmology and Visual Science, University of Chicago Medicine & Biological Sci- ences, shared some of their surgical pearls for DMEK. Matching the donor with recipient size Dr. Suh will usually perform a slightly larger descemetorhexis, 8 mm for a 7.75-mm DMEK graft, so there is not much overlap between donor and host. According to Dr. Veldman, it has been conclusively demonstrat- ed that overstripping, or placing a graft that is smaller than the area of excised recipient Descemet’s membrane, reduces the rate of rebubble in DMEK due to the minimization of graft overlap with native Descemet’s membrane. “Be- cause of this, I always remove slightly more Descemet’s mem- brane than I implant, typically a 7.5-mm graft inside of an 8-mm stripping,” he said. “I do adjust the graft size, typically smaller, in special circumstances such as under a failed penetrating kerato- plasty or when replacing a DSAEK as the available recipient graft bed dictates.” Dr. Lee uses an 8.5-mm trephine (Katena, Denville, New Jersey) to indent the epithelium of the recipient with centration around the pupil. This is stained with trypan blue. “I remove the Descemet's membrane and en- dothelium under the stained epithelial mark and inject donor DMEK tissue trephined at 8 mm so I have a 0.5 mm difference between donor and recipient,” he said. Pre-marked DMEK tissue Dr. Veldman said he is a big proponent of pre-marked DMEK tissue, having been involved in the development of the S-stamp. “It has improved the safety margin in DMEK through a reduction in the rate of upside down graft implanta- tions and importantly, in our study published in Ophthalmology, did not significantly impact clinical outcome parameters, including re- bubble rate and 6-month endothe- lial cell loss.” 1,2 He has been heartened by the number of physicians who have told him that the S-stamp enabled their successful and safe adop- tion of DMEK. “That said, there is some limited regional endothelial trauma induced secondary to the application of the S-stamp, so I will typically position the graft so that the S is superior, allowing more prolonged gas bubble coverage postoperatively,” he said. Dr. Lee uses pre-marked tissue in all DMEK cases. The eye bank pre-strips the tissue, leaving one marked edge attached, and place an “S” mark on the Descemet’s membrane side. “I think it is a godsend,” Dr. Suh said of pre-marked tissue. “It facilitates the surgery. For the be- ginning surgeons where the trypan blue can start to fade with longer unfolding times, the S-stamp will help with orientation.” She only uses S-stamp tissue at this point in her practice. Cases to watch for early in the learning curve Dr. Lee suggested avoiding young donor tissue, as it is hard to un- scroll in the eye. “Start out with pseudophakic patients rather than combined cataract patients,” he said. Additionally, he suggested avoiding highly myopic eyes with high axial lengths, as well as pa- tients with prior glaucoma surgery. Dr. Suh said she would avoid any eyes that have very deep ante- rior chambers, as the tissue is more difficult to unfold. “Also, any eyes that have had glaucoma surgery and vitrectomized eyes are better DSAEK candidates,” she said. “I stress to surgeons adopting DMEK to avoid eyes that have had prior vitrectomy,” Dr. Veldman A DMEK triple procedure, with cataract extraction, IOL implantation, and DMEK Source: Peter Veldman, MD