Eyeworld

EW FEATURE 50 Treating the cornea before cataract surgery • May 2017 by Liz Hillman EyeWorld Staff Writer Optimizing the ocular surface with amniotic membrane therapy AT A GLANCE • Amniotic membrane has been used for decades in various fields of medicine, including ophthalmology, for its healing properties. • More recently, amniotic membrane products have been used to optimize the ocular surface prior to cataract surgery, particularly to improve outcomes with advanced IOL technologies or enable patient candidacy for these refractive opportunities. • After applying an amniotic membrane product for a week, physicians varied on when they would take biometry measurements for IOL calculations, ranging from 2 weeks post-amniotic membrane therapy to 6 weeks or more, depending on the indication for use. • Educating patients on the presence and detrimental impact of their ocular surface disease on outcomes following cataract surgery, a once in a lifetime procedure, helps reduce the potential for resistance to treatment, the resulting delay in cataract surgery, and patient dissatisfaction following surgery. Dr. Donaldson said amniotic membrane has really taken hold within the last 5 years as multifocal and toric IOL technologies have demanded optimization of the ocular surface for positive patient outcomes. "If we have a patient who has severe dry eye, anterior basement membrane, corneal dystrophy, or Salzmann's degeneration, those patients make excellent candidates for ocular surface optimization with amniotic membrane," Dr. Donaldson said. "For the patients that have anterior basement mem- brane dystrophy and the patients who have Salzmann's degeneration, those patients are often undergoing superficial keratectomy 4–6 weeks before cataract surgery, so when we do a superficial keratectomy, I find the amniotic membranes can be a useful tool to supplement healing when we do that minor procedure to optimize their ocular surface. It can also be used with severe dry eye patients who have a lot of punctate epitheliopathy.… [In these cases, it] can help heal the surface and make the topography more regular making axis and power calculations more accurate." When to use it? While biologics like amniotic mem- brane can be a powerful tool, Dr. Desai said they are "not an end-all- be-all panacea." "Since ocular surface disease is typically seen as a chronic con- dition, all available modalities for treating the underlying contribu- tors to ocular surface disease must be instituted simultaneously. Since many of these treatments take time to perform and work before I can rationally proceed to a refractive cataract surgery, I often find myself counseling patients that due to co-existing problems, I want to do things not the fast way, but rather the right way," he said. Treatments Drs. Desai and Gupta consider prior to or in con- junction with amniotic membrane, Visual outcomes, clarity, and optical quality were also similar between the amniotic membrane and ban- dage contact lens groups. Paolin et al., on the other hand, wrote that the "benefits and safety features of [amniotic membrane] in ocular disorders are evident, based on long term data analysis of these procedures," which included epithe- lial ulceration, pterygium, keratitis, glaucoma, and bullous keratopathy. 4 Who to use amniotic membrane on? Although there are many indications for amniotic membrane use, when it comes to preparing the ocular surface prior to cataract surgery, Neel Desai, MD, director, Cornea and Refractive Surgery Eye Institute of West Florida, Tampa Bay, Florida, said candidates for cryopreserved amniotic membrane fall into two categories: (1) those with mild but visually significant ocular surface disease such as severe dry eye syn- drome or mild to moderate keratitis or (2) those with severe ocular sur- face disease such as severe keratitis, epithelial basement membrane dystrophy, or Salzmann's nodular degeneration. "In the first cases, placement of a PROKERA biological bandage [Bio-Tissue, Doral, Florida] alone may provide a potent anti-in- flammatory effect to quiet acute phase ocular surface inflammatory enough to obtain more accurate biometry," Dr. Desai said. "However, in the second cases, wherein the oc- ular surface disease has topographi- cally altered the surface and pre- cluded accurate biometric analysis, a superficial keratectomy followed by placement of a PROKERA graft is indicated." Kendall Donaldson, MD, medical director, Bascom Palmer Eye Institute, Plantation, Florida, and Preeya Gupta, MD, assistant profes- sor of ophthalmology, cornea and refractive surgery, Duke University Eye Center, Durham, North Caroli- na, also said they would use amniot- ic membrane for these indications to optimize the ocular surface prior to cataract surgery. other areas of medicine to promote healing. A. DeRöth began using fetal membranes—chorion and amniotic membranes—in ophthalmology in 1940 to treat symblepharon. A. Sorsby and H.M. Symons were the first, according to this article, to use the amniotic membrane without the chorion to treat eyes with chemical burns and saw "rapid recovery with few complications." "In surgical applications of the human amniotic membrane to the ocular surface, the transplanted amniotic membrane is known to facilitate ocular surface healing with minimal inflammation and scar- ring. The surface healing effect of amniotic membrane may be caused by several factors," according to this article, which explained that these factors include the amniotic membrane's basement membrane fa- cilitating migration, differentiation, adhesion, and longevity of epithelial cells. The composition of amniotic basement membrane is also similar to the conjunctiva in collagen and laminin structures, which can also help adhere and anchor epithelial cells, in particular to the stroma. The article also stated that amniotic membrane contains antiangiogentic and anti-inflammatory proteins and is known to inhibit fibrosis. As Rahman et al. put it during a session of the Cambridge Ophthal- mological Symposium in 2008, "the consensus is that [amniotic mem- brane] acts as a substrate or scaffold for host cells to populate and thus facilitate healing and repair." 2 Both Rahman et al. and Vlasov et al. 3 wrote that the exact mecha- nism of action of amniotic mem- brane to promote healing on the ocular surface is not fully known. What's more, Rahman et al. stated that while individual cases and series might tout the success of amniotic membrane, this is "not substantiat- ed in the few published randomized controlled trials." 2 Vlasov et al.'s prospective nonrandomized control trial published in 2016 involving PRK patients found that while amni- otic membrane helped speed corneal repeithelialzation, it did not do so faster than a bandage contact lens. 3 Amniotic membrane is known to contain healing properties F or more than 70 years, amniotic membrane has been used in various oph- thalmic conditions for its healing properties. Within the last few years it has become a tool in ocular surface optimization prior to cataract surgery, especially as premium IOLs require the most accurate of measurements to meet high patient expectations. According to the 2003 arti- cle "Human amniotic membrane transplantation: Past, present, and future," amniotic membrane, the innermost layer of the placenta, was originally used in skin transplants to treat burns and ulcers. 1 It later was used for various indications in continued on page 52

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