Eyeworld

EW FEATURE 54 All you need to know about cornea transplants • January 2018 20/25. At 4 years out now, Dr. Colby said the patient is still 20/20 with a clear cornea. According to Dr. Colby, this and a follow-up retrospective case series was a "proof of concept that it could work." 9 At the same time Gregory Mo- loney, MD, Sydney, Australia, was doing similar work, publishing his first case in 2015 and later describ- ing the use of a topical ROCK inhib- itor (ripasudil, a ROCK inhibitor not FDA approved in the U.S.) to "save" failing cases. 10–11 Dr. Colby said she has per- formed 10 such descemetorhexis cases, and all of her patients have chosen to obtain ripasudil on their own. Though she hasn't formally analyzed her data yet, Dr. Colby said anecdotally, it seems the ripasudil speeds endothelial clearance by a factor of two. "My average clearance in my original series was 3 months. The av- erage now is about 6 weeks; I've had some clear as quickly as 3 weeks," Dr. Colby said. A primary descemetorhexis without a graft is not for everyone though, Dr. Colby stressed. The patients this seems to work well on are Fuchs' patients with confluent guttae right in the center but the peripheral endothelium is preserved. Patients who would not do well with this technique include Fuchs' pa- tients who have wall-to-wall guttae out to the periphery and non-Fuchs' patients requiring a graft, such as those with pseudophakic bullous keratopathy. Preoperatively, patients need to be advised about the potential that the procedure will fail and they will need to have a traditional EK pro- cedure. Corneal edema within the first few months is also common, but Dr. Colby said she has not had a patient upset about that, explaining to them preoperatively this is likely to happen. Postoperatively, Dr. Colby starts patients on prednisolone six times a day and begins to taper them grad- ually after a week or two. If patients choose to obtain and use ripasudil, Dr. Colby said they start using it immediately postop. The procedure itself is "well within the skillset" of a cornea surgeon, Dr. Colby said, explaining that the descemetorhexis is the first step of any EK procedure, just smaller. She noted recent research that showed performing a capsu- lorhexis-like tear on Descemet's, rather than scoring and removing it, provides a smoother edge that may facilitate migration better than a jagged edge. "The field of cornea has seen an incredible revolution in the last 15 years. I think forward-thinking people will look at this carefully be- cause if you don't have to put cells from someone else and give them steroids for the rest of their life, that's a good thing," Dr. Colby said. "If a patient comes in and they've got a 720-µm cornea and there's no clear area, don't do it on that one, do a regular EK. But if a 45-year-old person comes in with symptoms with central guttae, what are you going to do? DMEK and give them a cataract, they'll be pseudophakic. The [primary descemetorhexis] procedure is quick, it's not resource intense." Dr. Colby said her team is gear- ing up to do a side-by-side compar- ison of DMEK in one eye and the descemetorhexis without a graft in the other, looking at outcomes, complications, patient satisfaction, and cost. "I know there's people even in this country who don't have access to a corneal surgeon for a trans- plant. … You can do this procedure and if it works that patient doesn't need regular follow-up with a cor- nea specialist, whereas even if you do the best EK in the world, most people still give steroids and there's risks of glaucoma and rejection and even though they're low with a pro- cedure like DMEK, they're not zero," she said. Cultivated corneal endothelial cells Dr. Mehta is part of a team that's hoping to eliminate the issue of donor tissue availability by cultivat- ing corneal endothelial cells from a donor that otherwise would have too low of an endothelial cell count to be transplanted. Dr. Mehta said their research has shown the ability to expand cells almost 240-fold. "With that number, it allows you to take one donor cornea and make enough cells to treat 90 pa- tients. Now we have something that could be a cell therapy approach," he said, and "you've alleviated this issue on donor stress." Preliminary research for this technique involved establishing the best media to create a proliferative, morphologically sound endothelial monolayer. 12 Dr. Mehta said they now use two different types of me- dia to culture cells, one for expan- sion and the other to stabilize the morphology of the cells. Animal testing has shown successful re-endothelialization with cultivated human donor cells, delivered either on a carrier or via injection. 13–14 For the carrier meth- od, endothelial cells are cultivated on a thin slice of human tissue—a biodegradable carrier is also in the works, Dr. Mehta said—and implan- tation and postoperative protocol follows exactly as in a DSEK. For injection, the patient's Descemet's is left intact, but Dr. Mehta uses a specially designed instrument from ASICO (Westmont, Illinois) to scrape off the endothelial cells. From there, the cultivated endothe- lial cells are injected and the patient lays face down for 3 hours. Dr. Mehta said there are certain indications where one technique might be favored over the other. For example, patients with no bullous keratopathy, no Descemet's scarring could fare well with cell injection, while a patient with a lot of central guttae would be better with cultivat- ed cells transplanted on a carrier. While culturing endothelial cells is resource intensive, Dr. Mehta said they performed analysis to determine the actual cost of cul- tured endothelial cell transplants vs. traditional donor transplants. 15 He said even if the number of possible cultured cells from one donor could only treat 60–70 patients, the cost to treat one cornea in this way is about $400, compared to $3,000 for a full donor cornea. "A lot of countries don't have access to tissue, but even if you do have access, that's still a significant reduction in cost," he said. At this point, Dr. Mehta said clinical trials have been approved for cultivated endothelial cells on a carrier and will soon begin enrolling. Separately and only for Fuchs' patients, Dr. Mehta described research with regenerative therapy, where the patient's own Descemet's membrane is removed and replaced with an acellular donor Descemet's that had endothelial cells removed. The patient's own endothelial cells at the periphery then migrate over Alternative continued from page 52 A patient with previously failed PK underwent PDEK and a single-pass four-throw pupilloplasty. Source: Amar Agarwal, MD continued on page 56

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