EyeWorld Asia-Pacific September 2015 Issue

51 EWAP DEVICES September 2015 by Michelle Dalton EyeWorld Contributing Writer Diagnosing dry eye disease In the future, clinicians will likely have a single test to quantify and distinguish the various types of dry eye, but for now, newer diagnostic tools are helping to confirm the disease D ry eye disease remains largely a clinical diagnosis, but there are now a number of diagnostic tools clinicians can use to help narrow the diagnosis. However, no one single test has yet emerged as the de facto standard, experts said. “All of the currently marketed tests have some value when used to confirm a clinical diagnosis of dry eye disease,” said Vincent P. de Luise, MD , assistant clinical professor of ophthalmology, Yale University School of Medicine, New Haven, Conn. “However, one should evaluate the sensitivity, specificity, and predictive value of a positive result and a negative result to assess the clinical value of each test. Understanding the role of dry eye diagnostic testing becomes as much a statistical discussion as it is a clinical one.” Which may be why the single most important factor remains subjective patient complaints and patient history, he said, adding that clinicians should continue to perform tear film and lid margin evaluation, tear breakup time (TBUT), vital dye staining, and even Schirmer testing, that have been the mainstay of diagnosis, along with subjective questionnaires. “A decision needs to be made early on as to whether the patient has aqueous phase deficiency, evaporative disease, or a combination of both, as the cause of their dry eyes,” Dr. de Luise said. “The problem is that currently none of the diagnostic tests is able to tell us which type of dry eye a patient has, or if there’s another disease involved (such as meibomian gland or goblet cell dysfunction).” Edward Holland, MD , director of cornea services, Cincinnati Eye Institute, and professor of ophthalmology, University of Cincinnati, Ohio, agrees and said the difficulty in diagnosis is because there are different types of dry eye. Each type of dry eye has a specific treatment regimen. He does believe that point of service testing helps clinicians diagnose dry eye and distinguish between aqueous tear deficiency and meibomian gland dysfunction. Newer diagnostics Dr. Holland recommends practices “empower technicians to use these new point of service tests” to help improve clinician efficiency, and believes the Tear Osmolarity System (TearLab, San Diego) is the “best initial screening test to diagnose whether there’s dry eye present or not. Having data available to the clinician before he or she sees the patient is extremely valuable in terms of improving our ability to diagnose and efficiently see patients,” he said. The threshold for a dry eye diagnosis is 308 mOsm/L on the TearLab system, but “you need a clinical diagnosis as well as a number,” Dr. de Luise said. “The number alone can be difficult to interpret, and can sometimes be asymmetric between eyes. In some cases, the osmolarity value can be in the normal range and the patient is clinically dry, or the value can be somewhat abnormal and the patient is clinically OK.” The InflammaDry (Rapid Pathogen Screening, Sarasota, Fla.) detects elevated levels of matrix metalloproteinase-9 and “it too has value if you are using it in the context of patient history and clinical slit lamp examination, but alone these tests can be difficult to interpret,” Dr. de Luise said. The InflammaDry can help diagnose those patients “with an inflammatory mediator in the cornea and be more specific to aqueous tear deficiency, but I don’t use that as the first screen,” Dr. Holland said. He thinks the “whole field” of meibomography is “going to be very valuable.” The LipiView system (TearScience, Morrisville, NC) uses tear interferometry to visualize and measure the thickness of the tear film lipid layer. “For patients, explaining MGD is difficult and didn’t always resonate, but when patients see an image of their truncated glands or completely obliterated glands, they start to understand why treatment is important,” Dr. Holland said. Dr. de Luise said “the astute clinician will notice on slit lamp evaluation whether the meibomian glands are abnormal, cheesy, stuck, closed, or inspissated.” Once the abnormality is confirmed and clinicians use the LipiFlow to help express the glands, “there’s benefit there,” he said. “The LipiView is more likely to be abnormal when you have a lipid phase abnormality than when you have an aqueous phase abnormality. A lipid phase abnormality usually confers evidence of evaporative type of dry eye. There is value to the TearScience test to distinguish evaporative from aqueous phase dry eye, but the slit lamp evaluation would have likely uncovered an abnormal tear film or if the TBUT was low,” Dr. de Luise said. Other potential tools For patients with more severe dry eye or Sjögren’s syndrome, there is the Sjo series panel of immunological markers designed to diagnose Sjögren’s, said Dr. de Luise. Dr. Holland believes the serum test for Sjögren’s evaluates the biomarkers that present earlier in the disease process and may allow diagnosis earlier in the disease course. Allergic eye disease is another important ocular surface disease that may benefit from newer diagnostics. Birmingham, Alabama-based Advanced Tear continued on page 53 “Clinicians still need to take a good history” - Vincent P. de Luise, MD