CORNEA 40 EWAP JUNE 2023 subconjunctival space around the autograft, though not under the graft, promotes healing. “It serves in that location as a biologic depot, using its anti-inflammatory and anti-fibrotic properties to reduce the growth of fibrotic cells that would cause recurrence, similar to the effect of mitomycin-C but without the risk,” Dr. Hovanesian said, noting that studies have found reoccurrence of pterygia after autograft alone vs. autograft plus amnion is 3–5% vs. 1%, respectively. “I regularly use amniotic membrane for double pterygium excisions or in patients with limited conjunctiva available for an autograft who are undergoing pterygium excision, high-risk corneal transplants, keratolimbal autografts, persistent epithelial defects after corneal ulcer resolution, and in a multi-layered fashion in microperforations in patients at high risk for patching or transplantation,” Dr. Houser said, adding another cause where she’d use amnion. “Glued and sutured amniotic membrane with a symblepharon ring in patients with active Stevens-Johnson syndrome or following chemical burns is also key in preventing long-term irreversible damage to the ocular surface.” Where use of amniotic membrane might be overkill, Dr. Hovanesian said, is in many cases of dry eye. He said that optometric colleagues often ask him about it, telling him that they’re hearing promotion about its use for dry eye patients. “Some of the reps seem to be over representing the utility of amniotic membrane for routine dry eye,” Dr. Hovanesian said, noting that “financially there is a strong incentive for reps to sell amnion and for doctors to use it, but that’s not what we’re here for.” There is promising anecdotal evidence for liquid amniotic cytokine drops, for example, but Dr. Hovanesian said that physicians prefer more rigorous science to support the use of these products. “There are cases where we feel desperate because whatever we use doesn’t seem to work. In those patients, it seems very unlikely that you’re going to harm them by trying products like this. If you get a positive result, you’re going to be doing them a big favor and you’re going to feel good about giving them that product,” Dr. Hovanesian said. Dr. Houser said that amniotic membrane might be a nice adjuvant though not always necessary in situations like autoimmune dry eye disease flares, which can respond well to amniotic membrane. However, it is important to initiate other long-term therapies such as autologous serum, cholinergic agonists, or anti-inflammatory drops in conjunction with amniotic membrane to prevent future flares. “Especially in cases where we would like to heal the ocular surface quickly, such as patients having a flare from their baseline dry eye or patients in whom we are trying to optimize the ocular surface prior to cataract surgery and who can’t tolerate steroid drops, amniotic membrane can be a useful adjuvant treatment to other longer-term maintenance therapies,” she said. While Dr. Houser thinks that amniotic membrane has a strong ability to heal the ocular surface, she doesn’t find it offers a lasting effect for patients with underlying structural abnormalities, such as epithelial basement membrane dystrophy. “While amniotic membrane could provide some short-term relief from the irritation or dryness, the underlying structural abnormality still remains and will continue to cause visual symptoms or discomfort until surgically addressed with superficial keratectomy or phototherapeutic keratectomy,” she said. EWAP Editors’ note: Dr. Houser is Assistant Professor of Ophthalmology, Duke University School of Medicine, Durham, North Carolina. Dr. Hovanesian is in practice with Harvard Eye Associates, Laguna Hills, California. Neither declared any relevant financial interests. ADVERTISER LISTING Oculus Page 44 www.cornealbiomechanics.com Feather Page 27 www.feather.co.jp/en/ APACRS Page 2, 5, 55, 56 www.apacrs.org
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