Eyeworld

52 | EYEWORLD | AUGUST 2019 C ORNEA PHARMACEUTICAL FOCUS Contact information Gregory: Darren.Gregory@ucdenver.edu Holland: eholland@holprovision.com Hovanesian: jhovanesian@harvardeye.com by Maxine Lipner EyeWorld Senior Contributing Writer can lead to slow healing, such as some cases of Salzmann's nodules. "I think the amnion makes the patient more comfortable when they have a large defect," Dr. Holland said. It also reduces secondary neovascularization, he finds. Amniotic membrane can mistakenly be used in limbal stem cell failure. "It doesn't sup- ply limbal stem cells," Dr. Holland said, adding, however, that when there is partial failure of two or three clock hours in which you want to scrape away abnormal corneal epithelium, it can be used to cover the area and allow healthy corneal epithelium to grow before conjunctiva invades. For pterygium surgery with amniotic mem- brane, John Hovanesian, MD, finds it exerts an antifibrotic and anti-inflammatory effect that reduces the risk of recurrence. Adding this to the equation with mitomycin-C reduces the re- growth rate from 50% to around 5%, he noted. The two different forms of amniotic mem- brane include cryopreserved and dehydrated. "With cryopreservation the tissue is frozen; it requires cold temperatures to maintain it, which creates a little more difficulty with shipping and storage, but it's effective," Dr. Hovanesian said. The dehydrated form is dried and terminally radiated to kill any contaminants but then is shelf-stable. "Because of that, there's a lower cost," he said. "There's not any real evidence that one is better than the other. Experienced F rom pterygium surgery to Stevens- Johnson syndrome and more, amni- otic membrane has a definite niche in ophthalmic practice. Amniotic mem- brane has two main roles, according to Darren Gregory, MD. "It can act like a bandage and provide an anti-inflamma- tory effect, or it can serve as a tissue substitute to fill a hole and provide a foundation that epithelium can grow onto," he said. For acute Stevens-Johnson syndrome, Dr. Gregory finds that amniotic membrane can be a real game-changer in preventing severe scarring complications. The membrane helps to quell inflammation and allow damaged conjunctiva to heal in with a relatively normal mucosal epi- thelium. "But there's a window of opportunity in the first week of the disease when it is most effective," Dr. Gregory said. Edward Holland, MD, finds that for recur- rent or very large pterygium where there might not be enough conjunctiva to do a free conjunc- tival graft, amniotic membrane can be a good conjunctival substitute. This is also true for oc- ular surface reconstruction such as limbal stem cell transplantation with a bare area of sclera that needs to be covered and in corneal surface reconstruction, especially where there's thinning and concern about potential perforation, he noted. He also uses amniotic membrane when he must scrape a large area of the cornea that Ocular uses of amniotic membrane About the doctors Darren Gregory, MD Associate professor of ophthalmology University of Colorado, Denver Edward Holland, MD Professor of ophthalmology University of Cincinnati John Hovanesian, MD Harvard Eye Associates Laguna Hills, California Watch Chris Starr, MD, and more from the 2019 ASCRS ASOA Annual Meeting

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