Eyeworld Daily News

EW SHOW DAILY 20 by Chiles Aedam R. Samaniego EyeWorld Asia-Pacific Senior Staff Writer 'New therapeutic dimensions' in corneal transplantation I f you ask a cornea specialist about innovations in corneal transplantation, said Neda Shamie, MD, Los Angeles, De- scemet's membrane endothelial keratoplasty (DMEK) will probably be the first topic to spring to mind. Endothelial keratoplasty, she said, evolved over the last 10 to 15 years, and although visual outcomes have improved and continue to improve over time, the 20/20, 20/15 acuities achieved by other anterior segment ophthalmic procedures re- main elusive. Ultrathin donor grafts may be better in that regard, while less stroma also means more rapid tissue and visual recovery; hence the excitement over DMEK. In the meantime, however, Descemet's stripping endothelial keratoplasty (DSEK) remains the "true and tested" gold standard for modern day selective corneal trans- plantation, said Dr. Shamie. Innovations continue to be made with DSEK as well, mainly in terms of techniques to avoid complications such as eccentric cutting of donor tissue resulting in full-thickness edges; donor graft dislocations; primary graft failure; and pupillary block. DMEK, on the other hand, provides more exact anatomical re- placement, though it is its potential for a lower rejection rate that is the key to its appeal for Michael D. Straiko, MD, Portland, Ore. Dr. Straiko designed a modified version of the glass Jones Tube (Gunther Weiss Scientific Glassblowing Co., Portland, Ore.) for use as an injector for the DMEK donor tissue. One difficulty with DMEK is in orienting the ultrathin donor tissue. Upside-down placement of grafts during transplantation is a major cause of graft failure. One method used by Dr. Straiko and his colleagues to prevent upside- down transplantation is the use of a stroma-side S-stamp. The S-stamp induces a 1.5% endothelial cell loss, but assures 100% tissue orientation. At the moment, there are a number of "standardized" DMEK techniques for use during transplan- tation—tapping on the cornea, for instance, causes a fluid current to flow within the anterior chamber that helps unroll donor tissue after insertion. However, Dr. Straiko said that he maintains the scare quotes because donor tissues in DMEK are so thin that it is difficult to predict their behavior. 'New therapeutic dimensions' This year's Richard L. Lindstrom, MD, Lecture was presented by a man who stands ahead of the curve of even the most advanced innovations in corneal transplantation. Known for a number of major discoveries regarding the corneal epithelium, Shigeru Kinoshita, MD, PhD, Kyoto, Japan, has turned his re- search onto the other side of the cornea: In his lecture, Dr. Kinoshita discussed "Stem Cell Therapy for Corneal Endothelial Disease." Upfront, he said, "Nobody really knows if corneal endothelium has stem cells." His approach, however, is certainly modeled on stem cell therapy, capitalizing on the ability of groups of corneal endothelial cells to differentiate and organize under the influence of a number of biochemical stimuli. The ultimate goal of surgical procedures such as DSEK and DMEK, he said, is essentially to increase endothelial cell density with good function. However, he envisions future therapy going beyond surgery, in two stages: early disease to be treated with rho-associated protein kinase (ROCK) inhibitor drops and advanced disease to be treated either with cell sheets or, more audaciously, cell injections. Cell injections are the ideal, being minimally invasive and requiring no artificial material on which to mount the cell. The procedure involves inject- ing 5x10 5 cultured human endothe- lial cells into the anterior chamber and having the patient lie face down for 3 hours. Dr. Kinoshita and his colleagues have, to date, conducted trials on three human subjects, with 1 to 3 months follow up, each of whom achieved very good out- comes. These "new therapeutic dimensions," said Dr. Kinoshita, are "coming soon." EW Editors' note: Dr. Kinoshita has patents pending with Senju Pharmaceutical Co. Ltd. and JCR Pharmaceuticals Co. Ltd. Dr. Straiko designed the modified Jones Tube but has no financial interests in the device. Dr. Shamie has no related financial interests. Tuesday, April 29, 2014 ASCRS Symposia Dr. Kinoshita delivers the 2014 Richard L. Lindstrom, MD, Lecture on "Stem Cell Therapy for Corneal Endothelial Disease."

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