MAR 2014

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E W CORNEA 92 March 2014 Using biomarkers to help quantify dry eye has potential, but more refinement is necessary W e're almost there— some of the newer dry eye diagnostic tools are moving the field f orward, but there's s till a way to go, according to some dry eye experts. For one, issues with reimbursement (and which ones should be reimbursed and which ones should be pass-along costs) are still being debated. Another issue (at least in university settings) is who will be administering the tests, said Richard S. Davidson, MD, associate p rofessor, and vice chair for quality and clinical affairs, University of Colorado Eye Center, Denver. " For the patients who come in symptomatic, the newer testing modalities can be helpful," he said. Anat Galor, MD, staff physician at Miami Veterans Affairs Medical Center, and assistant professor of clinical ophthalmology, Bascom Palmer Eye Institute, Miami, said one of the ongoing issues with dry e ye is the lack of a uniform defini- tion, which adds another layer of complexity onto how useful the newer diagnostic tools may be. "There are a lot of conditions that get called dry eye," she said. "Eyelid problems or chalasis can cause some symptoms of dry eye, but are not truly issues with the tear f ilm components themselves. When we check a biomarker such as osmo- larity, we get a lot of information that we don't know how to inter- pret. If there were a common etiol- ogy for dry eye, I think the use of biomarkers would be more useful." Patients like having something to follow, and in some cases having a number to watch may help facilitate treatment adherence, Dr. Davidson said. Biomarkers for inflammation Tear osmolarity has "great potential" but "it's not clear right now from the technology we have how well we can capture it," Dr. Galor said. TearLab (San Diego) measures osmo- larity at the inferior meniscus, Dr. Galor said, as the tear is more stable at that juncture. "But we also know what's probably more important is the osmolarity on the corneal surface." Because the tests are static and dry eye is a dynamic process, TearLab recommends administration three times in each eye to gauge the range—those with an unstable tear film will be "all over the board," and those with stable tear film will have a much tighter range, Dr. Galor said. "It's just not feasible in clinical prac- tice to check three times in each eye. But I think there's potential and my hope is that we will be able to improve the way it's measured." Insurance covers the osmolarity test, but often clinicians need to use multiple tests to determine appropri- ate treatments, she said. D r. Davidson said over time clinicians may have a way to better interpret the biomarkers, but it may be difficult for general ophthalmolo- gists to incorporate these types of tests into their daily practice. "Clinicians only have X amount to spend on new technology, so we have to pick and choose," he said. " You need to ask, 'Is it going to change my practice enough to make it worthwhile for me to invest?'" While TearLab's test provides an osmolarity number, InflammaDry (RPS, Sarasota, Fla.) identifies pa- tients with elevated levels of matrix metalloproteinase-9, an inflamma- tory marker for dry eye, in a binary f ashion. "Dry eye doesn't fit a yes or no picture," Dr. Galor said. "If someone has symptoms but comes back as 'no,' it's not clear how to use the in- formation—do you now tell the pa- tient they don't have dry eye? Or if the number comes back as 'yes,' but there are no symptoms, how should you counsel the patient? It's not clear to me how to use a yes/no test." If clinicians are unwilling to change how they manage patients based on test results, "then how good is the test?" Dr. Galor asked. Biomarkers are an important as- pect in the management of dry eye, she said, but "there's no way at this point to measure them in a way to be as clinically selective as we need." Dilemmas remain An issue that has confounded clinicians and industry alike is that numerous patients have severe symptoms and no clinical signs of dry eye, or vice versa—clinical signs abound, but the patient has no complaints or is asymptomatic. "I'm a tech person and I like new technology, but the biggest issue of using some of the newer tests is, can we use it on everyone?" Dr. Davidson said. "I do think for patients who have severe symptoms, it could be a way to track them." People with obvious moderate or severe dry eye will be expected to have osmolarity numbers in the higher ranges with more fluctuation within the ranges and a likely 'yes' by Michelle Dalton EyeWorld Contributing Writer Newer dry eye diagnostic tools show promise Device focus The TearLab Osmolarity System measures the osmolarity of human tears and helps diagnose dry eye disease. Source: Michael Lemp, MD The InflammaDry test registers positive if a red line appears in the result zone and a blue line appears in the control zone. This would indicate that there is a significant MMP-9 presence. Source: Rob Sambursky, MD 88-107 Cornea_EW March 2014-DL2_Layout 1 3/6/14 3:47 PM Page 92

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