Dry Eye has various possible causes, which advanced testing can help determine.
When the Tear Film & Ocular Surface Society released its Dry Eye Workshop II (DEWS II) report in May, it not only updated how we define dry eye but how we diagnose it. This process starts with questionnaires and, depending on the patient’s responses, may eventually warrant such tests as tear film osmolarity and interferometry.
Although a single test might seem more desirable, dry eye has various causes and symptoms, so there is no “one-test-fits-all” solution. Here are some of the tools and instruments we may use in dry eye disease diagnoses and treatment.
SURVEYS AND QUESTIONNAIRES
One of the most cost-effective ways to diagnose dry eye is to simply ask patients about their symptoms. With the confounding nature of dry eye, patients’ symptoms don’t always correlate to clinical findings. So, an assessment of a patient’s complaints and noted observations regarding their dry eye is valuable. Determining what course of treatment may be the best for a patient based on symptomology and likely adherence to the protocol is necessary.
There are a variety of validated surveys available. For example, the Standardized Patient Evaluation of Eye Dryness (SPEED) Questionnaire asks about the type, frequency and severity of symptoms. The Ocular Surface Disease Index (OSDI) asks about what symptoms the patient has experienced, if those symptoms have limited the patient’s ability to perform specific tasks, and in what conditions those symptoms occur.
Corneal topography, a tool readily available to many doctors, can tell a story regarding ocular surface health. For example, the OCULUS Keratograph 5M allows you to examine the meibomian glands and view morphological changes, evaluate the lipid layer, and measure tear film break-up time and tear meniscus height.
On corneal topography, mires will show a “smudging” or merging together due to an irregular ocular surface. The severity of the mires irregularity is reflective of the surface irregularity.
Additionally, when looking at an axial map, there can be false elevations due to patches of keratitis on the cornea. Missing or patchy areas on a topography map could also indicate reduced tear break-up time scores.
Inferior steepening that could mimic kerataconus may also manifest and could be related to epithelial dehydration. Lagophthalmos and exposure are common culprits in this finding.
Matrix metalloproteinase-9 (MMP-9), a cytokine produced by epithelial cells, is an indicator of inflammation in the ocular tissues and has been correlated with dry eye disease. The RPS InflammaDry Detector, which Quidel Corp. acquired from Rapid Pathogen Screening in May, detects elevated levels of MMP-9.
The test is inexpensive and easy for you or your employees to use in the office. Simply touch the conjunctiva with the pad of the tester and then use the solution provided, which contains antibodies to MMP-9. As the solution interacts with potential MMP-9, the indicator shows a positive or negative result. Results are available within 10 minutes, and the company says InflammaDry has 85% sensitivity and 94% specificity. InflammaDry indicates possible late-stage, or long-term, inflammation associated with dry eye.
The DEWS II definition of dry eye includes hyperosmolarity , or higher salt content, as one of the components of dry eye disease.
The TearLab Osmolarity System provides a different, yet valuable, data point for those with dry eye disease. Elevated levels of 300 or more milliosmoles/liter (mOsm/L) indicates a loss of homeostasis of the tear film. Inter-eye variability of more than 8mOsm/L indicates tear film instability.
Meaningful test results with osmolarity may be seen even in mild-stage dry eye disease. Objective testing such as this can help identify, track and manage patients by marking changes in levels over time and with treatment.
Most patients who have dry eye have evaporative dry eye from Meibomian gland dysfunction (MGD). And, patients who have aqueous-deficient dry eye (Sjögren’s and non-Sjögren’s) often have MGD. Thorough evaluation of the lids and related structures, such as Meibomian glands and lid margins, as well as lipid layer analysis, is important when it comes to dry eye management. Symptoms such as burning and fluctuations in vision can be related to reduced lipid layer thickness. Poor blinking habits are also linked to MGD and lipid irregularity.
The LipiView II from TearScience, which was recently acquired by Johnson & Johnson Vision, utilizes interferometry to quantify the lipid layer thickness of the tear film in real time. This technology can also detect incomplete blinking and performs high-resolution meibography to capture the structural integrity of the Meibomian glands.
A comprehensive diagnosis and treatment plan for dry eye and MGD requires an assessment of both the function as well as the structure of the meibomian glands.
These diagnostic technologies, although not inclusive of all testing available, summarize many of the advanced methods to help diagnose and treat our dry eye disease patients. Although there are no standalone tests for diagnosing dry eye, the data we gather from several or all of them allow us to best manage and help our dry eye patients.
Embracing the preventative model when it comes to dry eye is a novel concept, but with the technology outlined in this article, is absolutely possible. We owe our patients the opportunity to understand causative relationships and current disease state risk when it comes to conditions that can greatly affect one’s quality of life. Dry eye has the potential to impact millions of people. Instead of waiting to react to its aggravations, proactively test, treat and educate your patients for life.
Gina M. Wesley OD, MS, FAAO, is in private practice in Medina, MN.