Eyeworld

DECEMBER 2022 | EYEWORLD | 71 C colleagues treat) in the OUS studies, the prelim- inary findings are promising," Dr. Giegengack said, noting that corneal edema is reduced, and visual acuity is improved significantly. He added that cell therapy is a less complex procedure to perform than DMEK, and postop recovery for patients is shorter. "I'm hopeful that cell therapy will ultimately enable 'DMEK-like' improvements in vision to a larger group of patients," Dr. Giegengack said. This new cell therapy option could also be beneficial on a global scale by enabling easi- er access worldwide. Globally, corneal tissue supply is a big challenge, Dr. Giegengack said. "Even in the U.S., with an upswing in DMEK procedures, surgeons are requiring more specific donor tissue, so tissue supplies are running short," he said. "Cell therapy can alleviate these supply challenges. Dr. Kinoshita's exciting discovery was to get corneal endothelial cells to replicate in vitro (they do not regenerate natu- rally in vivo)." Dr. Yeu said that seeing this work in action has been incredibly gratifying. "It's exciting be- cause it's just cells plus a formulation of ROCK inhibitor." It allows for limbus-to-limbus adhe- sion of cells. With allograft transplants, "we're only able to replace the central 80%." As a re- sult, there are problems with peripheral edema, Dr. Yeu said, and those patients with peripheral pathology can't be treated well. "So far with the work we've done, these pa- tients are able to have corneal thinning that gets them to the same type of results that we see with DSAEK and DMEK by month 1 to month 6," Dr. Yeu said. She added that being able to get patients off steroids, or at least to minimal steroid use, is another benefit. This helps reduce some issues with ocular hypertension and glaucoma. "Not only are rejection rates lower, but the IOP issues are much lower, and these corneas look incredible," she said, adding that the possibility for patients to be able to survive on one transplant would be amazing. Dr. Yeu also commented on the technique used with corneal endothelial cell therapy, not- ing that it's even easier than DSAEK and DMEK because instead of a stripping, it's a polishing to remove residual endothelium using a silicone tip on a cannula. It's a familiar technique that any anterior segment surgeon can do. "It also opens up the opportunity to treat everything from early corneal edema to severe corneal edema as a first-line therapy," she said. Dr. Berdahl agreed that surgical accessibil- ity is an advantage of endothelial cell therapy. Endothelial keratoplasty is a highly technical procedure that's performed primarily by corneal surgeons, but endothelial cell therapy would be a more accessible technique. It would also likely have a decreased rejection risk because the cells are antigenically more neutral. "The proce- dure can control exactly how many endothelial cells are injected, the surgical technique is less technical, and we can avoid an air bubble in the anterior chamber and avoid the potential complications of flattening the chamber." In addition to Aurion Biotech, Dr. Berdahl mentioned that Emmecell is exploring endothe- lial cell therapy options. Other treatments Another advancement is Descemet's stripping only (DSO). Corneal endothelial cells will naturally expand to form tight junctions with other corneal endothelial cells, Dr. Giegengack explained, so when we strip away portions of Descemet's membrane, the remaining endotheli- al cells will grow and "morph" to fill in the gaps. Dr. Giegengack uses this procedure and thinks it works well for a small subset of Fuchs patients with focal central guttata and corre- sponding corneal edema that doesn't extend out to the periphery of the cornea. "You can remove that central area of guttata and treat with ROCK inhibitor drops," he said. "Peripheral endothelial cells can expand back into the center and fill in the gap. The advantage of this approach is that patients have the potential to regain vision without the risk of transplant rejection." However, he noted that DSO can take a long time to heal, and sometimes patients' vision isn't improved, and they do need to un- dergo a corneal transplant. He added that he's picky about when he performs DSO. Dr. Holland also explained that corneal endothelial cells do not naturally regenerate in vivo, and if cells die, the remaining cells will continued on page 72 References 1. Kinoshita S, et al. Injection of cultured cells with a ROCK inhibitor for bullous keratopathy. N Engl J Med. 2018;378:995–1003. 2. Numa K, et al. Five-year follow-up of first 11 patients undergoing injection of cultured corneal endothelial cells for corneal endothelial failure. Oph- thalmology. 2021;128:504–514.

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