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New View of Dry Eye Stresses Mechanisms Over Manifestations

Posted by australiandryeye on May 13, 2017 at 3:35 AM

The Tear Film & Ocular Surface Society (TFOS) presented the conclusions and recommendations of the TFOS Dry Eye Workshop II (DEWS II) during a special session of the Association for Research in Vision and Ophthalmology (ARVO) 2017 Annual Meeting in Baltimore, Maryland, yesterday.

TFOS is a nonprofit, global organization that aims to improve understanding of the composition and regulation of the preocular tear film and its function in maintaining the cornea and conjunctiva, preventing infection, and preserving visual acuity. The group is a collaboration among scientists, clinicians, and industry professionals.

Definition Updated


The first dry eye workshop, held in 2007, "launched an increase in basic and clinical research to better understand dry eye, which affects 40 million people in the [United States], 10 million severely," David A. Sullivan, PhD, senior scientist at the Schepens Eye Research Institute/Massachusetts Eye and Ear and associate professor at Harvard Medical School, Boston, told Medscape Medical News.

The DEWS II report, which will be published in late June in Ocular Surface Journal, presents "a global consensus of the epidemiology, mechanisms, diagnosis, management, impact, and classification" of the condition, Dr Sullivan said. "We're distributing the report to hundreds of thousands of eye care practitioners in many languages," he added.

Among the key points in the new report is an updated definition of dry eye that is more mechanistic. Whereas the 2007 definition emphasized the symptoms of the disease, the 2017 definition describes the underlying causes of the disease: "Dry eye is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles," Jennifer P. Craig, PhD, MCOptom, the workshop vice-chair, said in a TFOS news release.

A Shifting View

Fifteen to 20 years ago, dry eyes were attributed, logically, to insufficient water. Since then, "we've learned a tremendous amount. Now we know that androgens affect the lid and the main lacrimal glands, and regulate the Meibomian glands," Dr Sullivan said.


In Sjogren's syndrome and complete androgen insensitivity syndrome, the Meibomian glands do not make enough oil to prevent evaporation of tears, triggering a cascade of events that ultimately damages the ocular surface. "The tears do not start to concentrate, and receptors on the cornea trigger sensations of pain and discomfort. This decreases the ability of the eye surface to hold water and increases the instability of epithelial cells, which may die," Dr Sullivan continued. Meanwhile, cytokines pour out and trigger inflammation.

The new description of the disease grew out of the realization that markers of dry eye reflect "a significant role for osmolarity and inflammation," said chair of the session J. Daniel Nelson, MD, associate medical director for specialty care for HealthPartners Medical Group and Clinics in St Paul, Minnesota. Since the first report, the technical literature related to dry eye has almost doubled, he added.

"Classically, we'd say that dry eye is aqueous or evaporative. We know now that most people have a combination," Dr Nelson said.

The new definition also recognizes a role for the neurophysiology in the sensory aspect of the disease, which emerged from the disconnect between signs and symptoms in some patients. An individual with signs, but not symptoms, may have a pre-dry eye situation, Dr Nelson suggested. The reverse — patients with symptoms but no signs — may actually have neuropathic pain and not dry eye.

Underlying Causes


The new report also delves into causes of dry eye, which include autoimmune diseases, eye surgery that damages the ocular surface, use of certain types of drugs (diuretics, beta-blockers, and topical medications for glaucoma), blepharitis, eyelids that turn in or out, overuse of contact lenses, and prolonged staring at a lit screen, which reduces blinking.

At the DEWS II session, researchers also discussed the design of clinical trials to assess new drugs. "Dry eye doesn't have a cure, and there isn't a treatment for Meibomian gland dysfunction, which is the major cause," Dr Sullivan said, adding that drugs approved by the US Food and Drug Administration are anti-inflammatories. "They deal with the situation downstream, but not the underlying problem."

Meanwhile, Dr Nelson shared with Medscape Medical News that he helps patients take "a Sherlock Holmes approach" to identifying actionable environmental triggers such as seasonal allergies, exposure to irritants at work, and cosmetics, creams, and cats. "A woman may go to bed with facial cream on, but anything touching the lower lid gets into the tear ducts very quickly," he said. Cat saliva on human bedding deposits allergens that can trigger dry eye even after the cat has relocated.

Some patients simply learn to live with dry eyes, perhaps by minimizing environmental triggers, Dr Nelson noted.

Paradoxically, dry eye is the leading cause of visits to eye care practitioners, yet one study estimates that slightly more than half of affected individuals have not sought professional care, Dr Sullivan said. He adds that "the prevalence has not been fully appreciated."

More than 150 clinicians and researchers worked on the 2017 report. "It's great bringing people from all over the world together to move our understanding forward and have increased research translate into new strategies to improve the quality of life for people with this common disease," Dr Sullivan added.

Numerous companies fund TFOS, including Alcon, Novartis, Shire, Allergan, Bausch + Lomb, Akorn, CooperVision, Dompé, Horus Pharma, Lubris BioPharma, Oculeve, Sun Pharma, TearLab, SIFI, Johnson & Johnson Vision Care, Carl Zeiss Meditec/ZEISS Group, Quint Health, Scope Ophthalmics, and Senju. The authors have disclosed no other relevant financial relationships.

TFOS DEWS II Report. May 7, 2017.


http://www.medscape.com/viewarticle/879675

Categories: Research, News

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