Dry eye decision tree – 10 years after DEWS

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A DRY EYE DISEASE DECISION TREE

With the DEWS guidelines almost 10 years old, new approaches are needed.

BY JASON SCHMIT, OD.

I am sometimes asked about medical decision-making by students, interns, fellows, or optometry colleagues. “How did you come up with that decision in managing that ocular surface disease case?” I give the answer appropriate to the particular case, but I also note that sometimes it comes down to experience. “That’s why they call it ‘practicing medicine,’” I say. “At first, it might seem that we are ‘practicing’ with patients. But, with experience, decision-making becomes more instinctual and less like practicing.”

The first step in developing the most appropriate treatment plan for a patient with dry eye disease (DED) is to correctly categorize the stage and type of DED the patient exhibits using the available technology. Then address the patient’s symptoms using the appropriate evidence-based therapies.

To make the right diagnosis, start with a complete DED examination. Think of this as analogous to diagnosing and managing glaucoma. Primary open-angle glaucoma is a diagnosis of exclusion: the patient’s intraocular pressure, nerve fiber layer, visual fields, cup-to-disc ratio, corneal hysteresis, anterior angles via gonioscopy, medical and family history, and other ancillary factors are all assessed. Treatment is based on whether aqueous production must be reduced or outflow must be improved. Then, over time, the patients is reassessed to determine if the patient is reaching target pressure or not and whether the visual field is stabilizing. If not, the treatment plan must be made more aggressive. A similar process goes on in the care of patients with DED.

In 2007, a committee of optometrists, ophthalmologists, and scientists convened the International Dry Eye WorkShop (DEWS). The aim of DEWS was to outline the information needed to fully diagnose and treat patients with DED. In the almost 10 years since that effort, there have been significant advances in the field of DED. This article presents an update on how we approach the management of this disease where I practice, Vance Thompson Vision.

MULTIFACTORIAL DISEASE

Reports of the prevalence of DED varies in the literature, but is estimated to affect 30 to 40 million adults in the United States, or about one out of every seven adults, and it is twice as common in women as men.1,2

DED, as defined by the DEWS, is “a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability, with potential damage to the ocular surface. It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface.”3 As many as 50% of patients with DED are asymptomatic, so it is important to screen all patients for DED.4 This can easily be done using one of the DED questionnaires that are readily available, such as the Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire.5

It is also important to understand that there are two types of DED: evaporative and aqueous-deficient.6 Purely aqueous deficient DED is relatively rare, occurring in only about 10% of cases.7 Meibomian gland dysfunction (MGD) has been shown to be evident in about 86% of all DED cases, far outweighing purely aqueous deficient DED. Many patients have a combination of both conditions.7 Three forms of MGD have been recognized: hypersecretory, hyposecretory, and obstructive, with obstructive the most common.

The incidence of MGD is thought to be rising because of an increase in incomplete blinking among patients.8 As use of computers and handheld mobile devices and smartphones increases, users tend not to blink as frequently or as completely as previously. The squeeze action that occurs with a blink is the force needed to release oil from the meibomian glands. With incomplete blinking, the oils in the glands become stagnant, hyperkeratinization of the meibomian ducts occurs, and the glands start to atrophy, a phenomenon termed disuse atrophy.9 As this cycle occurs over long periods of time, further gland atrophy occurs, and, with the reduction of the lipid content of tears, evaporative DED develops.

This understanding is important to frame your approach to treating patients with DED; everyone must be assessed for DED. Much of the initial management will be based on the results of testing for osmolarity and inflammation. Most cases of DED are evaporative in nature due to deficiencies of the meibomian glands, and therefore gland imaging is a crucial component of assessment.

INFLAMMATORY CASCADE

When we delve into what is happening in the inflammaory process at the cellular level, we find a cyclic cascade of events occurring. Intercellular adhesion molecule 1 (ICAM-1) is a protein found in the epithelial and endothelial cells of ocular tissues. ICAM-1 is found in excess in patients with DED. Adhesion molecules aid in recruiting other mediators toward sites needing attention.

In this case, ICAM-1 is sending signals for other inflammatory T cells to flock to its site to promote inflammation. A receptor on inflammatory T cells called lymphocyte function- associated antigen 1, or LFA-1, adheres to ICAM-1, activating the T cells and releasing cytokines that further increase ICAM-1 expression, leading to the continuation of the cycle of inflammation (Figure 1).10

GRADING DED

One of the products of the DEWS effort was a schema that helps practitioners to grade the level of severity of DED (Table 1). What is nice about this classification system is that it directly corresponds to both subjective and objective testing that eye care providers routinely utilize in clinical practice.

Two factors that this system does not include, however, are osmolarity (per the TearLab test) and inflammation (per the InflammaDry test), both of which are included in the DEWS definition of DED. In modern practices, osmolarity can be assessed using the TearLab Osmolarity Test (TearLab) and inflammation can be assessed with the InflammaDry test (Rapid Pathogen Screening). With the further understanding of the inflammatory element of DED, measurement of inflammation is crucial for the success of treatment and management. Because imaging devices that perform meibography, such as the LipiView II (TearScience) and Oculus Keratograph systems, are now available, this information can also be assessed and used to determine the proper course of action.

A BETTER NOMOGRAM

The guidelines for managing DED based on the 2007 DEWS findings are now almost 10 years old.11 The DEWS treatment recommendations are stratified according to the severity of the disease (Table 2).

At Vance Thompson Vision, we have been diligently working on developing a nomogram to better classify the diagnostic levels of DED (based on severity and progression), as well as an algorithm tool for eye care providers. This tool would guide treatment decisions taking into consideration the diagnostic technologies now available and the treatments that might not have been available at the time of the DEWS report almost a decade ago.12

This nomogram includes a three-part process: clinical indicators, treatment options, and engagement (Figures 2-4) The first part (clinical indicators) includes all of the structured and standardized testing needed to diagnose patients into the correct stage of DED. The second part (treatment options) then allows the clinician to better manage the patient, by instituting the proper treatment regimen paired with the corresponding diagnostic tests.

Finally, the third part (engagement) helps to set the standard for having patients return for follow-up care. (There can be nearly $400 in additional revenue annually when patients return for their scheduled DED follow-up appointments. In addition, incorporating a DED retail center into the practice can be another significant source of revenue.)

CONCLUSION

DED is a long-term, chronic disease that affects tens of millions of people in the United States, compared to about 2 million suspected glaucoma patients in this country.13 DED can disrupt the quality of life for many, and it is estimated that people spend up to $2 billion dollars annually on DED products and treatments.14

Recognizing signs and symptoms early and educating patients on the root causes of their DED problems is critical to increase patient compliance with your selected treatment plan. Specifically targeting the causes of each patient’s DED with products and treatments designed to improve function will make a difference in your patient’s well-being and quality of life.

DED is multifactorial, but it is defined by abnormal osmolarity and inflammation. If you incorporate new testing modalities into your practice and follow a systematic protocol for management of the disease, hope- fully your decision-making will be less like “practicing medicine” on your patients. You can potentially make your patients, and yourself, much happier.

Jason Schmit, OD

In private practice specializing in oculoplastics, aesthetics, cataract, and refractive clinical care at Vance Thompson Vision in Sioux Falls, South Dakota
President of ConceptualEyes, an ophthalmic consulting company specializing in improving operational excellence and overall practice growth
jason.schmit@vancethompsonvision.com
Financial interest: none acknowledged

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