Eyeworld

EW CORNEA 56 May 2018 by Rich Daly EyeWorld Contributing Writer Is an evidence- based definition and contemporary classification system for dry eye disease consistent with an emerging theory that blepharitis and dry eye are one condition? A n emerging theory holds that blepharitis and dry eye are one simple condi- tion: dry eye blepharitis syndrome (DEBS). First outlined in a paper in Clinical Ophthalmology, DEBS runs counter to dominant views of dry eye disease as complicated, with an overlapping disease presentation that stems from multiple etiologies.¹ "In a nutshell, bacteria produce biofilm, which thickens with age, and becomes inflammatory," said James Rynerson, MD, president and CEO of BlephEx (Franklin, Tennes- see), a co-author of the initial DEBS analysis. "The biofilm accumulates within all of the lid structures and leads to the stages of DEBS." The theory posits that the pro- gression of dry eye starts with mei- bomian gland dysfunction (MGD), which also includes aqueous defi- ciency, said John Hovanesian, MD, medical director of BlephEx, and in private practice, Beverly Hills, California. Support for the DEBS theory stems from the known colonization and growth of bacteria on the lid floor and lid floor changes with age, said Hank Perry, MD, professor of ophthalmology, Hofstra University Medical School, Hempstead, New York. "Positive cultures increase with age, as does dry eye." "The differences in subtypes of bacteria can reflect in terms of the pathogenicity that occurs in patients," Dr. Perry said. "For exam- ple, some bacteria can be relative- ly non-pathogenic, and even an 80-year-old patient can be relatively asymptomatic while a child patient can have significant meibomian gland disease and dry eye." The view is further supported by the well-established efficacy of antibiotics to help patients' meibo- mian gland disease, he said. "Meibomian gland disease is the majority of what we consider dry eye at this time," Dr. Perry said. "When we look more carefully at the biofilm we know there's a com- munication that occurs between the bacteria in which a certain concen- tration can form toxins." DEWS II implications In 2017, the Tear Film & Ocular Surface Society published DEWS II to achieve a global consensus on various aspects of dry eye disease (DED).² Among its goals was an up- dated definition and classification of DED, and examination of the epide- miology, pathophysiology, mecha- nism, and impact of the disorder. Drs. Perry and Hovanesian viewed DEWS II as bolstering the DEBS theory. "It's consistent with the pub- lication that mostly directs that dry eye comes from an underlying cause," Dr. Hovanesian said. "I'm all in favor of the DEWS classifications, but I think it dove- tails exactly with inflammation and that inflammation can occur in childhood and becomes more frequent as time progresses," Dr. Perry said. In contrast, Dr. Rynerson said DEBS cannot be interpreted accord- ing to DEWS II because "DEWS II is simply wrong." "The DEWS committee still does not understand the existence or the importance of biofilm development along the lid margin," Dr. Ryner- son said. "Without understanding biofilm, dry eye cannot be explained and leads to all of the confusion and complexity that has impeded our understanding and treatment of dry eye disease for decades." More research Additional needed research should examine Staph species virulence factors as the most important cause of inflammation to the meibomian glands, Dr. Perry said. "Different strains of Staph produce different virulence factors (toxins), some benign and some highly inflammatory," Dr. Perry said. "The structures in the lid mar- gin succumb to these toxins over time, just as the human body does systemically in a much shorter time. Perhaps there may be a way in the future to identify pathogenic strains and replace them with benign strains especially on the more severe patients." Like any theory, DEBS can and should be challenged by research studies that will confirm or refute the idea, Dr. Hovanesian said. "One increasingly convincing set of observations is that when we treat the biofilm at an early stage we do seem to see an arresting of dry eye," Dr. Hovanesian said. "We are now focusing more attention on Biofilm and lid margin disease T he publication of the TFOS DEWS II report and the increasing awareness around the importance of ocular surface optimization and dry eye manage- ment in patients, especially in the period prior to cataract surgery, has encouraged many ophthalmologists to seek a better understanding of how to manage their patients' dry eye disease. Understanding the pathophysiology behind dry eye disease helps with determining what therapies will benefit the patient. An interesting theory that will be explored in this "Cornea editor's corner of the world" is that blepharitis and dry eye are one condition on a spectrum with a foundation based on bacteria biofilm production and accumulation on the lid margins. John Hovanesian, MD, James Rynerson, MD, and Hank Perry, MD, lend their expertise in the discussion of this topic to explore the clinical impact and future directions. Clara Chan, MD, Cornea editor Severe anterior blepharitis showing end-stage folliculitis and diffuse lash loss Prominent expression of altered meibum occluding meibomian gland orifices and chronic lash folliculitis Source: Hank Perry, MD Cornea editor's corner of the world

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