One of the most frequent reasons for patient visits to eye care practitioners is dry eye disease (DED). In the United States, more than 30 million people have DED. The burden of DED for the US health care system is estimated to be almost $4 billion.¹ What’s more, diminished productivity due to DED leads to a loss of more than $55 billion for overall US society.

The Tear Film & Ocular Surface Society Dry Eye WorkShop II (TFOS DEWS II) report, the successor to the landmark TFOS DEWS report published in 2007, achieved global consensus concerning multiple aspects of DED, including the following:

• updating the definition and classification of DED;
• evaluating the epidemiology, pathophysiology, mechanism, and impact of DED;
• developing recommendations for the diagnosis, management, and treatment of DED; and
• recommending the design of clinical trials to assess future interventions for DED treatment.

In a process that spanned almost 3 years, the TFOS DEWS II report involved the efforts of 150 clinical and basic research experts from around the world. These experts used an evidence-based approach and a process of open communication, dialogue, and transparency to increase the world’s understanding of DED.

REDEFINING DED

The new definition for DED devised by the TFOS DEWS II report is as follows:

“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.”

HIGH PREVALENCE, HIGH IMPACT

Patients with moderate to severe DED commonly experience significant pain, role limitations, poorer general health, and, often, depression. The management of this disorder is complicated due to its multifaceted etiology. Although the majority of patients with DED show some relationship between symptom severity and signs, it is well recognized that a large percentage of patients will exhibit conflicting signs and symptoms. Identifying the major causative factors behind DED is critical to the appropriate management of individual patients.

One of the most striking features of DED is that it occurs more frequently in women than men. Indeed, sex, gender, and hormones play a major role in the control of ocular surface and ocular adnexal tissues and in the difference in DED prevalence between women and men. Gender and biological sex influence DED risk, DED presentation, immune responses, pain, care-seeking behaviors, service utilization, and many other facets of eye health.

According to the TFOS DEWS II report, the prevalence of DED, with and without symptoms, ranges from 5% to 50% in different areas of the world. DED prevalence based on signs alone indicates that DED prevalence may reach 75% in some populations.

Consistent risk factors for DED include age, sex, race, meibomian gland dysfunction (MGD), Sjögren syndrome, androgen deficiency, pollution, use of certain medications, computer use, and contact lens wear. Probable risk factors for DED include diabetes, viral infection, pterygium, refractive surgery, and allergic conjunctivitis.

MECHANISMS

The core mechanism of DED is evaporation-induced tear film hyperosmolarity, which damages the ocular surface and initiates inflammation. Obstructive MGD, in turn, is the most common type of evaporative DED. Key events in obstructive MGD are reduced tear quality (ie, increased viscosity) and hyperkeratinization of the terminal duct, leading to duct obstruction, duct dilatation, and atrophy of the glands.

Of particular interest, DED can be caused by a number of iatrogenic interventions, including topical and systemic drugs, contact lenses, cosmetic or aesthetic procedures, and ocular surgery.

CLINICAL RECOMMENDATIONS

The TFOS DEWS II report makes recommendations for how to diagnose and determine the subtype of DED in a clinical setting. Videos demonstrating many of the recommended diagnostic procedures will soon be available on the TFOS website (www.TearFilm.org). The report also features a management algorithm for the treatment of DED and proposes recommendations for the optimal design of clinical trials to evaluate potential therapies for DED.

The TFOS DEWS II report was published in the July issue of The Ocular Surface.^2-12 A downloadable version of the document is available for free on the TFOS website. Translations of the report will soon be available in numerous languages, including Chinese, French, German, Italian, Korean, Portuguese, Romanian, Spanish, Turkish, and Vietnamese.