Eyeworld

91 January 2017 EW MEETING REPORTER The evolving field of keratoplasty Following a day of didactic courses and wet labs, ACS 2016 began its scientific program with a series of symposia, one of which tackled "Penetrating Keratoplasty/Complex Keratoplasty/Corneal Graft Rejec- tion." Session chair Charles N.J. McGhee, MD, Auckland, New Zealand, summed up the lessons learned with 10 years of experience in practice and from studies in New Zealand in his talk "Indications, Complications and Outcomes of Corneal Transplantation in a Tertia- ry Centre: Auckland 2000–2010." Regarding penetrating keratoplasty, Dr. McGhee presented 1994–2003 data from the New Zealand Eye Bank, which covered 1,820 penetrat- ing keratoplasties over the 10-year period. The 1-year survival in these cases was about 87%, with irrevers- ible rejection at 7%. From the New Zealand Eye Bank data, Dr. McGhee said that the independent risk fac- tors for decreased survival were iden- tified as at least one episode of rejec- tion, active inflammation at surgery, corneal neovascularization, small and large graft sizes of either <7.25 mm or >8.5 mm, preexisting glau- coma, and an indication of trauma or regraft. Dr. McGhee also present- ed data comparing the incidence, severity and outcomes of traumatic wound dehiscence after penetrat- ing keratoplasty and deep anterior lamellar keratoplasty (DALK) from cases performed from 2000 to 2014. Out of 1,163 penetrating grafts, the data showed 28 cases of traumatic dehiscence (2.4%). On the other hand, out of 131 DALK grafts, there were no cases of traumatic dehis- cence. While this, he said, is not a statistical difference, it is certainly a clinical difference that might cause one to lean toward undergoing DALK rather than a penetrating graft. The limitations of penetrating keratoplasty include donor material, rejection, suture issues, microbial keratitis, ametropia/astigmatism, delayed recovery, and steroid-re- lated changes in IOP. In contrast, DALK provides the advantages of a "layered" approach to dealing with pathology, an essentially extraocular procedure, preserving the endotheli- um intraoperatively, and a reduced, "low-maintenance" follow-up, with reduced risk of significant rejection, reduction in topical steroid, and ear- lier suture removal. DALK, however, is technically more difficult and time consuming. Dr. McGhee said that in the early part of the learning curve, DALK has twice the risk of failing (p=0.02), with 19% of DALK failures within 30 days. Overall, Dr. McGhee said that the data from practice and studies in New Zealand highlights 25 years of changing indications, reflecting the revolution in lamellar techniques. In 2016, he said, there remains a role for penetrating keratoplasty, a well-es- tablished technique with more than 100 years of experience. Globally, it still represents approximately 50% of keratoplasties, though it remains mainly limited by allograft rejection and induced ametropia. As reflected in the change in indications, many of penetrating keratoplasty's roles have been supplanted by lamellar procedures, but ongoing indica- tions for the next several years will include advanced keratoconus (hydrops), endothelial dysfunction with established stromal changes, full thickness scars and penetrating corneal trauma, regrafts for PKPs with poor shape or extreme astigma- tism, and DALK conversions. Plenary "puts the pieces together" In "Putting the Pieces Together: Approaches in the Investigation and Management of Atypical Corneal In- fections," Elmer Tu, MD, Chicago, took the opportunity of giving the first plenary lecture of the meeting to take a breather from big data and instead highlight the value of what he called "small" and "very small data." "We'll go the opposite way from big data," Dr. Tu said; rather than following the trend toward big data forward, he began by looking into the past. England in the 1800s, Dr. Tu said, was "somewhat of a miserable experience." For centuries, he said, there had been no real im- provement in terms of life expectan- cy, with most people dying in their 30s and 40s, "much like a mayfly after mating." This was in no small part due to various European pan- demics, such as the bubonic plague and cholera. Compounding the hell of the period's level of technology, hygiene, and abbreviated life spans, there was no real way of stopping these pandemics other than by iso- lating subjects and allowing them to die out. At the time, the prevailing theory for transmission of disease was the miasmatic theory—diseases such as cholera, it was believed, were transmitted through exposure to "bad air," typically emanating from foul or rotting organic matter. Dis- eases were thus transmitted through breathing rather than direct contact or ingestion. This theory, Dr. Tu said, had held throughout history, and as an intervention in the case of cholera epidemics in London, the city began directing human waste away from homes and into the river Thames. Enter John Snow—who, as it turns out, knew something. A skeptic of the miasmatic theory, Snow had previously written on his theory of the origin of cholera outbreaks in 1849. He identified a particular water company supplying South London that he associated with more than 50% of deaths in all of London. Following the Soho cholera outbreak in August 1854, the Reverend Henry Whitehead, miasmatic theorist and self-styled "myth buster" of his age, met John Snow through a local commission to investigate cholera. He immediately set out to disprove Snow's theory. However, after interviewing local residents, the Reverend Whitehead mapped the subjects around a single water source—and ultimately came continued on page 92 Edward Holland, MD, delivers the Asia Cornea Foundation Medalist Lecture on the topic of management of severe ocular surface disease.

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