Eyeworld

EW CORNEA 46 June 2016 by Liz Hillman EyeWorld Staff Writer these studies show that the tech- nique is at least safe and "as good as CLET," and data suggest SLET may be superior to CLET in the pediatric population. Dr. Amescua said that in his 5 years using SLET, he noticed that it seems to work best in patients with LSCD induced by chemical burns or trauma. In patients with autoimmune conditions such as Stevens-Johnson syndrome and mucous membrane pemphigoid with asymmetric presentation that are clinically quiet or under control with systemic immunosuppression, SLET was not effective, Dr. Amescua observed. "In an eye that's quiet with a wet ocular surface and good eyelid function, [SLET] works very well," he said. Dr. Amescua recommended that those performing SLET use a cryo- preserved human amniotic mem- brane (the membrane placed on the ocular surface of the recipient eye and used as a substrate for the donor tissue), rather than a dry preserved amniotic membrane. "For this procedure, you need a really smooth surface, and you don't get that with dry preserved," he said. Like Dr. Basu, Dr. Amescua said SLET is far less expensive and more accessible than CLET, but he said he doesn't think it will replace CLET completely. "There has been resistance toward SLET from some surgeons who would rather wait for CLET to The minimum follow-up period was 1 year, with some patients being evaluated up to 4 years postop. The study found that 95 cases resulted in a successful outcome, and 67% of these cases had a best corrected vi- sual acuity of 20/60 or better, which was a "significant improvement" compared to the patients' baseline. The researchers did not observe any long-term negative effects in the opposite eye, which served to donate the stem cells. The most common complication, occurring in 23 of the 125 cases, was progres- sive conjunctivalization coming back even after SLET. Progressive symblepharon, hemorrhage under the human amniotic membrane, loss of the SLET transplant, keratitis, and corneal melting were other less common complications. The study also stated that suc- cess rates were similar for both the experienced surgeon and trainees. A separate, multicenter study published this year in the British Journal of Ophthalmology reached similar conclusions. 3 Eight centers in 3 countries—India, the United States, and Mexico—performed SLET on 68 patients with clinical success in 57 cases with a median follow-up of 1 year. "I think we have enough evi- dence to show that [SLET] works and can offer very good long-term results in patients with unilateral chemical injury," Guillermo Amescua, MD, Bascom Palmer Eye Institute, Miami, said, adding later that the data from Six years ago, Dr. Basu, Virender Sangwan, MBBS, LV Prasad Eye Institute, and their col- leagues pioneered a new technique: simple limbal epithelial transplanta- tion (SLET). This procedure involved transplanting the stem cells directly from patients' healthy donor eye into their affected eye. 1 "What we do here is combine the advantages of the previous procedures. We take the same very small amount of tissue that is taken in [CLET] and instead of cultivating the stem cells in the lab," which Dr. Basu said gets very expensive and limits the patient's opportunity for treatments based on lab availabil- ity, "we cultivate it directly on the patient's eye." LSCD, regardless of its cause, is a potentially sight-threatening con- dition in which the cells responsible for replacing the corneal epithelium are lost or fail to function. Dr. Basu said a corneal transplant is not an option for these patients because the stem cells are not transferred in such a procedure—hence the need for a limbal stem cell transplant of some kind instead. Until recently, SLET was lacking in long-term safety, efficacy, and reproducibility data. Dr. Basu and his colleagues published a study in Ophthalmology earlier this year, detailing the clinical outcomes of SLET in 125 eyes (65 adults and 60 children) with LSCD resulting from ocular surface burns. 2 Long-term data for simple limbal epithelial transplantation suggests it's consistently safe and effective T he effects of limbal stem cell deficiency (LSCD) can be significant. Photographs of such cases show the con- junctiva growing over the iris and pupil, effectively blinding the person. Though this is one of the most extreme effects, pain and a lack of clarity are more common, among other symptoms. Treatment for this condition, which can result from traumatic injury, infection, or inflammatory conditions, began almost 3 decades ago with con- junctival limbal grafting. Then ex vivo cultivated limbal epithelial transplantation (CLET) became an additional treatment option about 10 years later. While conjunctival limbal graft- ing has its safety issues, CLET can be location and cost prohibitive, said Sayan Basu, MBBS, LV Prasad Eye Institute, Hyderabad, India. "If you think of conjunctival limbal grafting as a very radical procedure, where you take a lot of tissue, and if you think of ex vivo cultivated limbal epithelial trans- plantation as a complex procedure, the alternative to this is simple," he said. Positive outlook for new technique to make LSCD treatment safer, cheaper, and more widespread Surgeons at the Ocular Surface Workshop III perform live SLET surgery on a patient with limbal stem cell deficiency. A wet lab demonstration of a limbal biopsy, which is part of the SLET procedure, performed on a goat eye Source: Ocular Surface Workshop III, Tej Kohli Cornea Institute, LV Prasad Eye Institute

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