Diagnosing Dry Eye

Simple and advanced tools help uncover the signs and symptoms of this common condition

■ By Melissa Barnett, OD, FAAO, FSLS

In my practice at the University of California, Davis, a substantial portion of my work involves ocular surface disease, dry eye and fitting specialty contact lenses. I am extremely aware of the studies demonstrating that patients discontinue contact lens wear, most often due to discomfort, at a rate of 13% to 20%.¹

As such, I look at treating dry eye and ocular surface disease not only as a way to keep their eyes healthy, but also to keep them in their contact lenses, which, in turn, leads to satisfied patients and contributes to practice revenue.

To identify patients who need dry eye treatment, I use all the available tests and tools — from simple to advanced — an overview of which follows.

Patient Education & Questionnaires

Too often, patients aren’t forthcoming about their symptoms, which is why patient education and clear communication are critical to uncovering problems. In fact, informative brochures and questionnaires are the first step of diagnosing dry eye. I’m a firm believer in having informative brochures in the reception area to help start the dry eye conversation. I always have them available, along with a questionnaire, such as the SPEED or OSDI. The paper questionnaires work for me, but for practices that have digital devices for patients in the waiting room, an OSDI app is available.

The questionnaire sets the stage for my second step: asking questions. Many patients are clearly symptomatic, reporting dry, watery, burning eyes, and so on. But others say their eyes feel fine. I always ask those patients with “fine” eyes if they experience blurry or interrupted vision, and more often than not, they say yes. Typically, these patients are the ones whose vision improves to 20/20 if I instill an artificial tear or ask them to blink repeatedly behind the phoropter. In my experience, it is this group of patients in particular who can be kept in contact lenses longer as a result of diagnosing and treating dry eye at an earlier stage.

In addition to asking patients about symptoms, it’s important to ask environmental and lifestyle questions. We know the myriad contributors to dry eye, but it’s important that we convey that knowledge to our patients. For example, I talk with patients about aspects of their home and work environments that may contribute to their symptoms. In some cases, simple changes, such as turning off the ceiling fan, help significantly. And although patients may not be able to discontinue systemic medications that dry their eyes, they may be able to switch from oral allergy medications to ocular allergy drops or nasal sprays.

Clinical Examination

When I examine a patient, I evaluate:

• Adnexa (dermatological inflammation, dermatochalasis, rosacea)

• Eyelids and eyelid margins (infectious, inflammatory, allergic, physiologic [lagophthalmos], blepharitis, meibomian gland dysfunction [MGD], lid-wiper epitheliopathy, giant papillary conjunctivitis)

• Conjunctiva (staining, chemosis, conjuctivochalasis)

• Cornea (topographical, hypoxia, secondary infectious/inflammatory, dystrophy).

A growing amount of research suggests that MGD is the most frequent cause of dry eye.² Therefore, it is important to identify MGD or rule it out. Non-obvious MGD (NOMGD) may be present, so I always push the lower eyelid gently to express the glands, which often reveals a problem — even in otherwise normal-appearing eyelids.

Clinical Testing

■ Schirmer I and II: I sometimes use the Schirmer test to evaluate aqueous tear production, especially for patients referred by rheumatologists because they usually request a Schirmer’s test. In theory, Schirmer I, performed with anesthetic, evaluates baseline secretion, while Schirmer II, performed without anesthetic, measures baseline plus reflex secretion. More than 10 mm of moisture on the filter paper after 5 minutes is considered a normal test result.

■ Corneal and conjunctival staining: I always have my patients remove their contact lenses so I can use a staining dye. Fluorescein will stain to reveal defects in the corneal and conjunctival epithelium. Rose bengal will stain dead conjunctival cells or cells unprotected by a normal mucin layer. It also stains the conjunctiva more than the cornea.

The degree of staining correlates well with the degree of aqueous tear deficiency, tear breakup time (TBUT), and reduced mucus production by conjunctival goblet cell and non-goblet epithelial cells. Lissamine green works by the same mechanism as rose bengal but tends to be less irritating for the patient.

If I see staining in a patient who wants to wear contact lenses for the first time, I treat the ocular surface first, then schedule the contact lens fitting for a later date, especially if multifocal lenses are the goal.

Another helpful aspect of staining in contact lens patients is that it reveals lid wiper epitheliopathy (LWE).³ (The “lid wiper” is the portion of the upper eyelid marginal conjunctiva that sweeps the ocular surface during blinking.) LWE is a frequent finding when patients have dry eye symptoms without accompanying dry eye signs (Figure 1).

Figure 1. Flipping the upper eyelid reveals staining associated with lid wiper epitheliopathy.

■ Tear breakup time: TBUT is useful to evaluate at every visit when examining the ocular surface. It correlates with both aqueous and evaporative tear deficiency.

Although TBUT has been criticized for a lack of repeatability and standardization, I find it very useful for monitoring visit-to-visit improvement in a way that is illustrative for patients. A TBUT of less than 10 seconds is abnormal, indicating tear film instability. A TBUT of less than 5 seconds is closely associated with dry eye symptoms. It is important to keep in mind that anesthesia decreases TBUT, and fluorescein can destabilize the tear film.

■ Point-of-care testing: Point-of-care testing is something many optometrists, including myself, find helpful for making dry eye diagnosis more accurate and efficient. Two such tests are InflammaDry (RPS) and the TearLab Osmolarity System.

InflammaDry is based on a quantifiable value of the amount of matrix metalloproteinase-9 (MMP-9) in the tears. MMPs are proteolytic enzymes produced by stressed epithelial cells on the ocular surface, and MMP-9 is a marker for inflammation. The test has been shown to significantly and positively correlate with corneal fluorescein staining scores and abnormal superficial corneal epithelia as seen with confocal microscopy.⁴ Results are obtained in 10 minutes and easy to interpret. A red line is positive (>40 ng/ml of MMP-9) and a blue line is negative.

The TearLab osmolarity test is similarly quick and easy to use, requiring only nanoliter volumes of tear fluid. It has been shown to be a solid metric for diagnosing and classifying dry eye disease.⁵ Osmolarity values above 308 mOsms/L are indicative of dry eye. Because the results are a quantitative numerical value, this test is helpful for engaging patients in their care as we work toward improvement.

■ Anterior segment imaging: Recent advances in anterior segment imaging devices, such as corneal topographers and tomographers, have included ocular surface capabilities, such as tear meniscus assessment. In my practice, I use a Pentacam (Oculus) to evaluate tear film regularity. Other available devices include the LipiView II interferometer (TearScience), which measures lipid layer thickness, evaluates blink rate, and enables visualization of meibomian gland structure to aid in earlier detection of MGD. The Medmont topographer is also able to evaluate the tear film.

The More Data the Better

Dry eye affects many patients, not just contact lens wearers. Today’s varied diagnostic tools provide valuable information and, when coupled with an open patient dialogue, will not only improve diagnostic and treatment abilities, but help boost your bottom line, creating a win-win for everyone involved. •

REFERENCES

Dr. Barnett is a principal optometrist at the University of California, Davis Eye Center in Sacramento, where she specializes in anterior segment disease and specialty contact lenses. She is a Fellow of the American Academy of Optometry, a Diplomate of the American Board of Certification in Medical Optometry (ABCMO) and serves on the Board of Women of Vision (WOV), Gas Permeable Lens Institute (GPLI), Ocular Surface Society of Optometry (OSSO) and The Scleral Lens Education Society (SLS).