Eyeworld

EW FEATURE 52 Treating the cornea before cataract surgery • May 2017 have become less common in oph- thalmology in favor of the former unsutured varieties. "Unfortunately, there is the false impression that all amniotic mem- branes are the same in their char- acteristics, qualities, and efficacy," Dr. Desai said. "It would be more accurate to view the amniotic mem- brane as a carrier for the pertinent biological factors producing the anti-inflammatory, anti-fibrotic, and pro-healing effects." "Cryopreservation allows retention of PTX-3 and the high-mo- lecular weight HC-HA complexes, whereas dehydration processes denature these key molecules and render them largely undetectable in many of the dehydrated membranes where, instead, proinflammatory low-molecular weight complexes remain," he added. Both Drs. Gupta and Desai said they prefer cryopreserved amniot- ic membrane because it has both anti-inflammatory effects as well as a barrier function. PROKERA's cryopreserved amniotic membrane, which is held in place by a poly- methyl methacrylate (PMMA) ring, is the only one approved by the U.S. Food and Drug Administration as a wound-healing corneal bandage. PROKERA also comes in a Slim version and a thicker Plus version, which is longer lasting. Dr. Gupta said some patients might not tolerate PROKERA's PMMA ring and in these cases, dehydrated amniotic grafts can work well, being placed on the ocular surface and covered with a bandage contact lens. Dr. Desai explained further that PROKERA might be contraindicated in patients with filtering glaucoma blebs, for exam- ple. IOP Ophthalmics (Costa Mesa, California) has several dehydrated amniotic membrane products. Dr. Donaldson said most of her patients tolerate the PROKERA Slim well, but she explained that she aids in this tolerance with a taped tarsorrhaphy. "We're not taping the eye shut, it just makes the upper lid slight- ly ptotic so that it droops enough that the blink is incomplete," Dr. Donaldson said. "It's very rare now that I have a patient not tolerate it. But, of course, it looks like they have a droopy lid, so you do have to warn them ahead of time." Patients also need to be warned that they will experience decreased depending on the patient's patholo- gy, include artificial tears, immuno- modulators (e.g., steroids, cyclospo- rine, lifitegrast), nutraceuticals, and warm compresses. If the patient has meibomian gland disease, ocular ro- sacea, or evaporative tear deficiency, Drs. Desai and Gupta advise Lipi- Flow (TearScience, Morrisville, North Carolina) coupled with Intense Pulsed Light (IPL) therapy. Dr. Gupta said she'll treat ocular surface inflammation with topical therapies first, but if the condition doesn't improve with that treat- ment, she's apt to turn to amniotic membrane as a next resort. "One caveat is in patients in whom I am looking for a relatively rapid response—often [amniotic membrane] can rapidly restore the surface, but you will often still need to treat the underlying dry eye for long-term control," Dr. Gupta said. Dr. Donaldson, who started using amniotic membrane in the operating room in residency, later employing it in the office setting, at Bascom Palmer where Scheffer Tseng, MD, PhD, founder of Bio-Tis- sue, was then a faculty member, expressed a similar sentiment. "If they're already on several treatments and already maximized their medical regimen, then I would move on to this," she said. "A lot of times, they don't want to wait that long for their cataract surgery and they just say, 'Let's do everything I can now to move this forward as quickly as possible,' and then I would recommend going forward with the PROKERA. You have to have that conversation with the patient to see how aggressive they want to be and how quickly they want to move forward." According to Dr. Desai, cau- tion must be exercised when using amniotic membrane in the presence of infectious keratitis prior to a response to antimicrobial therapy or in cases where a yet-undiagnosed ocular or systemic condition is the underlying etiology for the apparent ocular surface disease. According to Paolin et al.'s eval- uation of data from more than 5,000 amniotic membrane patches over a 12-year period from a tissue bank, there were no adverse reactions re- ported, "confirming the high safety margin assured by this therapy." 4 What kinds of amniotic membrane products are there? There are two major types of amni- otic membrane: cryopreserved and dehydrated. Sutured surgical grafts Optimizing continued from page 50 Appropriate use of an amniotic membrane product in pre-operative ocular surface optimization prior to refractive cataract surgery. Significant EBMD detrimental to accurate pre-operative biometry and lens selection (top). A superficial keratectomy with placement of Prokera for 3 days (middle) produced quality healing without haze or scar (bottom) allowing candidacy for and accurate selection of a presbyopia-correcting IOL. Source (all): Neel R. Desai, MD continued on page 54

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