Eyeworld

APRIL 2023 | EYEWORLD | 83 C by Liz Hillman Editorial Co-Director About the physicians Kourtney Houser, MD Assistant Professor of Ophthalmology Duke University School of Medicine Durham, North Carolina John Hovanesian, MD Harvard Eye Associates Laguna Hills, California "You have to address the underlying issues," Dr. Hovanesian said. "Amniotic membrane may still be appropriate in these cases, but you've done the patient little good if the surface breaks down 2 weeks later because the eyelid is not closing." Dr. Hovanesian and Dr. Houser said they sometimes use amniotic membrane after pteryg- ium excision as well. While both use conjuncti- val autografts, Dr. Hovanesian said research has found that putting an amniotic membrane in the 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 fi- brotic 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 auto- graft alone vs. autograft plus amnion is 3–5% vs. 1%, respectively. A mniotic membrane, in its various forms, has several ophthalmic appli- cations, but it is also, at times, being marketed for indications that don't have a lot of evidence in the scien- tific literature and/or that have other proven alternatives, according to physicians. Kourtney Houser, MD, said there are a number of companies that offer dehydrated and cryopreserved amniotic membrane. John Hovanesian, MD, said amniotic cytokine extract drops are also being produced. Overall, amniotic products are sought after for their anti-fibrotic and anti-inflammatory properties that facilitate healing. Just when use of these products makes sense, however, is up for debate. Dr. Houser said there are several scenarios when she will consider using amniotic mem- brane, such as in cases of persistent epithelial defect occurring spontaneously or following procedures such as superficial keratectomy, PTK, PRK, band chelation, or crosslinking. Patients with etiologies that are at high risk for prolonged healing following epithelial remov- al, such as autoimmune disorders, underlying severe dry eye, or neurotrophic keratopathy, can benefit from application of amniotic membrane concurrent with one of the above procedures, she said. "I will occasionally use amniotic membrane in high-risk patients in conjunction with superfi- cial keratectomy. If the epithelium is not healing appropriately and nearly completely healed at 1 week following a procedure involving epithe- lial removal such as superficial keratectomy or PTK, I will often place an amniotic membrane to facilitate healing," Dr. Houser said. "I also find amniotic membrane to be helpful in patients with neurotrophic ulcers and often will use it in conjunction with other treatment modalities such as serum tears or a tarsorrhaphy or while awaiting approval and receipt of cenegermin." Dr. Hovanesian also mentioned the use of amniotic membrane for persistent ocular surface defects but said that it's important to address underlying causes of those defects. For example, if a patient has an eyelid defect that is causing the surface issue, the issue will persist if the eye- lid problem is not solved. Amniotic membrane: when it's useful vs. overused Placement of dehydrated amniotic membrane as a graft after pterygium removal Source: John Hovanesian, MD continued on page 84

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