EyeWorld India June 2017 Issue

June 2017 EWAP CORNEA 51 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- Tissue, 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, caution must be exercised when using amniotic membrane in the presence of infectious keratitis prior to a response to anti-microbial 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 evaluation of data from more than 5,000 amniotic membrane patches over a 12-year period from a tissue bank, there were no adverse reactions reported, “confirming the high safety margin assured by this therapy.” 4 What kinds of amniotic mem- brane products are there? There are two major types of amniotic membrane: cryopreserved and dehydrated. Sutured surgical grafts have become less common in ophthalmology in favor of the former unsutured varieties. “Unfortunately, there is the false impression that all amniotic membranes are the same in their characteristics, qualities, and efficacy,” Dr. Desai said. “It would be more accurate to view the amniotic membrane 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-molecular 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 amniotic 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 polymethyl 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 example. 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 slightly 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 vision with PROKERA, but Dr. Donaldson pointed out that Bio- Tissue now offers PROKERA Clear. The PROKERA Clear may be very useful in a monocular patient that cannot afford to compromise vision in their only eye. The central portion of the PROKERA Clear is devoid of amniotic membrane to preserve vision. If a patient won’t tolerate PROKERA because of the ring, Dr. Donaldson said she’ll use another form of bandaged contact lens, though it won’t be as therapeutic. When to take measurements? While amniotic membrane products lead to “rapid re-epithelialization without scarring or haze” in a week or less, Dr. Desai said, it can take up to 4 weeks for the epithelial remodeling to complete. The physicians interviewed for this article varied slightly on when they would take measurements for IOL power calculations. Dr. Desai said biometry could be completed a month after “Prokeratectomy,” while Dr. Donaldson said she’d wait 3–4 weeks, and Dr. Gupta said she would wait at least 6 weeks, especially in the setting of prior epithelial defects, to allow epithelial remodeling to take place, checking measurements serially to make sure keratometry values were stable before proceeding with surgery. Dr. Donaldson also noted that after having the amniotic membrane product applied for a week, she directs her patients to then continue their prior ocular surface regimen, which might include artificial tears and other medical therapy. Putting amniotic membrane in the context of the bigger picture, Dr. Donaldson said cataract surgery requires a partnership with the patient in order to achieve our very best outcomes. “They have to understand that cataract surgery is a once-in- a-lifetime experience per eye, and we need to make the investment in time and effort to choose the best IOL possible,” she said. “We want to do everything we can in our power to optimize the surface and optimize the choice of lens that’s going into their eye because it’s going to last forever. Once you create this partnership with the patient, they don’t get frustrated with taking the extra time to do this…Fortunately, with all the technology—the imaging technology, the therapeutic technology, and the diagnostic technology—that we have nowadays, we can use those things to help patients understand better so that they can take part in this treatment process to make their cataract surgery outcomes the best possible.” EWAP Editors’ note: The physicians interviewed have financial interests with Bio-Tissue. References 1. Thomas, J. Human amniotic membrane transplantation: Past, present, and future. Ophthalmol Clin N Am . 2003;16:43–65. 2. Rahman, I, et al. Amniotic membrane in ophthalmology: Indications and limitations. Cambridge Ophthalmological Symposium. Eye . 2009;23:1954–61. 3. Vlasov, A, et al. Sutureless cryopreserved amniotic membrane graft and wound healing after photorefractive keratectomy. J Cataract Refract Surg . 2016;42:435–43. 4. Paolin, A, et al. Amniotic membranes in ophthalmology: Long term data on transplantation outcomes. Cell Tissue Bank . 2016;17:51–8. Contact information Desai: desaivision@hotmail.com Donaldson: KDonaldson@med.miami.edu Gupta: preeya.gupta@duke.edu