Dry eye since DEWS

By Laura M. Periman, MD

Decades ago, clinicians viewed dry eye disease (DED) management as simple, targeted and direct. Some viewed DED as an unimportant nuisance. Theoretically, this was partly due to: the misperception of it being a simple disease; the immature scientific understanding of its chronic inflammatory nature; and the paucity of interventions. Clinicians considered DED a simple problem of insufficient tears that should respond to simple artificial tears supplementation.

Natural risk factors include age, hormone status and climate stresses (such as wind, cold or low humidity). However, a healthy lacrimal functional unit (LFU) should maintain tight homeostatic control of the ocular surface despite these conditions. The modern era has expanded the list of stresses on the LFU: 2011 Market Scope data projected a 10% increase in DED prevalence over the next 10 years. The ever-increasing time spent at computers and smart devices, homeostasis-threatening accoutrements including medications, contact lens use, artificial indoor environmental exposures and air travel make DED appear as a consequence of modern living. However, it is not an inevitable consequence.

In 2007, the authors of the DEWS Report, a landmark paper that compiled and summarized the best scientific evidence, generated the Core Mechanisms of Dry Eye Disease Figure (See diagram). This figure appears complicated, but it coalesces the ideas that inflammation is the hub of the CORE mechanisms, and aqueous deficiency dry eye and evaporative dry eye are the cause and consequence of inflammation. The DEWS Report also provides some insights into future clinical technologies, namely tear osmolarity, which is a known independent driver of inflammation.

The most important point to discern from this chart, which beautifully explains dry eye’s complex dysfunctional cacophony, cause and consequence, is that you can enter the DED cycle at any point. Once the process begins, inflammation begets inflammation in a chronic, self-perpetuating downward spiral. The numbers in the figure correspond with the numbered blocks below, which list the diagnostic and therapeutic advances accumulated since 2007.

The much-anticipated DEWS II Report is slated for publication in the next 12-24 months. It will include new advances and scientific studies, perhaps along with helpful treatment algorithms incorporating new clinical tools.

DED may seem more complicated, but as we measure, understand and define in detail its true nature, clinical management will once again become direct, targeted and simple. OM

The Definition and Classification of Dry Eye Disease: Report of the Definition and Classification Subcommittee of the International Dry Eye Workshop (2007). The Ocular Surface. Reprinted with permission; Elsevier.

Laura M. Periman, MD, is a cornea and refractive surgery trained ophthalmologist in Redmond, Wash. Her interests in immunopatho-physiology started as a research and development associate at Immunex Corp. in the early 1990s. She can be reached at lauramperimanmd@gmail.com.