29 EyeWorld Asia Pacific | June 2024 by Ellen Stodola, Editorial Co-Director Treatment of Limbal Stem Cell Deficiency Identifying and treating patients with limbal stem cell dysfunction or deficiency can be a challenging process. Several physicians discussed how they handle these patients, including which techniques are available for mild to more severe disease. Bennie H. Jeng, MD The first thing to know is the difference between deficiency and dysfunction, Dr. Jeng said, because limbal stem cell deficiency means there are no more cells left, or at least not in certain areas. Dysfunction could mean that there are cells, but they just aren’t working, he said. “I make that distinction because there are cases, for example, in contact lens-associated limbal stem cell dysfunction, if you give patients a contact lens holiday, they could recover, or other cells nearby could recover or repopulate.” While Dr. Jeng said it’s hard to give an actual incidence or prevalence, the concept of limbal stem cell dysfunction or deficiency is underdiagnosed in general because if you don’t look for it, you won’t find it. If you look carefully, 5–10% of people with chronic contact lens wear have some mild degree of limbal stem cell deficiency or dysfunction, he said. Dr. Jeng said that contact lens intolerance and taking a contact lens holiday is the first rung of treatment for this condition. Severity escalates when the stem cells are wiped out from disease or inflammation. It becomes a problem, Dr. Jeng said, when there are more than 4–6 contiguous clock hours of deficiency because then the surface can’t re-epithelialize correctly. The cells that then populate the surface are conjunctivalized epithelial cells rather than clear corneal cells, he said. Many of these things—like chemical burns, Stevens-Johnson syndrome, and autoimmune disorders—that lead to LSCD are already being managed by corneal specialists. Dr. Jeng said treatment of every individual patient is different. It depends on the degree and how active the disease is. “I actually had a patient who had 11 clock hours of stem cell deficiency from a chemical insult in the past,” he said. “That 1 clock hour allowed him to re-epithelialize in the very center of his cornea, and I had him in a scleral lens to protect the rest of stem cells, and for years he managed just fine with that.” Dr. Jeng said scleral lenses are usually his first go-to if there is some degree of stem cell issue, though this may not work for every patient. By understanding the pathophysiology of limbal stem cell dysfunction or deficiency, Dr. Jeng said that performing a Penetrating Keratoplasty (PK) or any sort of keratoplasty does not fix the problem because the problem is the stem cells, not the cornea itself. “If it’s an isolated stem cell issue, then keratoplasty doesn’t have a role.” So, if scleral lenses don’t work, you’re left with really two options, Dr. Jeng said. One is a keratoprosthesis, and the other is a stem cell transplant. Dr. Jeng has used keratoprosthesis for stem cell deficiency. “You have to be very careful about who you choose because, even though it’s an indication for doing the procedure, they still have to be able to epithelialize,” he said. “If they can’t, doing a KPro, you’re asking for trouble. If it can’t epithelialize up to the optic, then you can’t do it because they’ll melt and have a bad outcome.” For this reason, Dr. Jeng is very conservative when choosing a KPro CORNEA
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