Eyeworld

EW MEETING REPORTER 140 Reporting from the All India Ophthalmological Society, February 16–19, 2017, Jaipur, India studies, there were no significant difference between amniotic mem- brane and the alternative. But didn't Dr. Dua just offer convincing rationale for why the amniotic membrane works? The problem, he said, is that there are in fact a number of contradictory molecules associated with the amni- otic membrane. For instance, while you could (and many do, as Dr. Dua did earlier in his talk) highlight the membrane's anti-inflammatory activity via IL10 and IL1ra, there are also pro-inflammatory molecules such as IL6, IL8, and prostaglandins. Moreover, there are wide intra- and interdonor variations often not controlled for. Intradonor variations include the epithelium, which could range from cuboidal to columnar; thickness and transparency, with the tissue growing thinner and clearer away from the placenta. Interdonor variations include age and race; the mother's gravidity and parity; extraneous conditions such as trial or onset of labor; and duration of pregnancy. In both cases, processing, handling, and preservation may also vary. Dr. Dua said that while anec- dotes and case series show success with amniotic membrane transplan- tation, bear in mind that people tend to report successes, not failures, and successful transplants make good pictures. European and non-European popu- lar traditions," Dr. Dua said, quoting Carlo Ginzburg's 1966 historical study, The Night Battles: Witchcraft and Agrarian Cults in the Sixteenth and Seventeenth Centuries. "It crops up as a link to the wandering soul, of the prematurely deceased, a bridge, a point of passage between their world and that of the living," he said. Dr. Dua cited an example from as late as the 19th century in London, where an advertisement in the London Times dated 1835 said: "A Child's Caul to be disposed of, a well-known preservative against drowning, & c., price 10 guineas." Certainly superstitions around the amniotic membrane persist in various cultures around the world even today, but could there be more to the widespread, cross-cultural mystification of this tissue? There might indeed be sorcery involved—though not, given the an- ecdotal "evidence" Dr. Dua offered early in his lecture, what you might have come to expect. Fast forward to the 20th and 21st centuries. Following a literature search via PubMed, Dr. Dua found just 33 randomized controlled trials for "amniotic membrane" and "eye." The studies varied greatly and encompassed various conditions including glaucoma, pterygium, and ocular burns, yet the results were largely the same: in almost all the Amniotic membrane—science or sorcery? In the first of Friday's President's Guest Lectures, Harminder Dua, MD, Nottingham, United King- dom, laid out the science that has accumulated over the last century in support of amniotic membrane transplant. The earliest recorded use of amniotic membrane in medicine, he said, is by J.W. Davis in 1910. Dr. Davis used amniotic membrane for skin burns. This was rapidly followed by use in other forms of surgery including, in 1940 by A. de Roth, in ophthalmology. Why is it used? Science provides some convincing answers justify- ing its continued use. Studies have shown that the basement membrane of amnion has a collagen structure similar to human conjunctiva and cornea, while the stroma is avascular like the cornea. Amniotic membrane has other qualities that make it seem ideal for patches and grafts: it is translucent yet metabolically active; it contains neurotrophic growth factors; it reduces chemokine expression in- duced by bacterial toxins, exhibiting some modulation of cell signaling and protein expression; and it reduc- es inflammation. But really, Dr. Dua said, the way the membrane works is by providing a new substrate for epithelial cell migration and adhesion. It inhibits fibrosis, promotes epithelialization and wound healing, inhibits vas- cularization, has antibacterial and anti-inflammatory activity, and is non-immunogenic. All these characteristics make amniotic membrane seem almost… magical. Indeed, there is an extensive amount of what you might call counterscientific literature behind the amniotic membrane—sorcery predating all the science. Long ago, Dr. Dua said, people once believed that a child born with a caul—wrapped in its amniotic membrane—would probably be notorious in some way. "The caul was considered to be the seat of the 'outer soul' in several March 2017 View videos from AIOS 2017 EWrePlay.org Mohan Rajan, MD, Chennai, India, discusses a technique for avoiding capsular rupture in cases of white cataracts. continued on page 142

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