Eyeworld Supplements

EW NOV 2013 - Supported by TearLab, TearScience, Nicox, and PRN

This is a supplement to EyeWorld Magazine.

Issue link: https://supplements.eyeworld.org/i/203232

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Page 3 of 7

4 Advanced tear film testing: Improving diagnosis and patient treatment Assessing new information from the chemistry of the tear film by Edward J. Holland, MD Osmolarity Major etiological causes of dry eye F or most ophthalmologists, the way we diagnose ocular surface disease hasn't changed much in the past 20 years. However, there are two main reasons why we should consider new diagnostic tests: 1) We are not as good of diagnosticians as we think we are, and we could all benefit from additional information to help us make accurate diagnoses. 2) New point-of-service tests will make us more efficient, better clinicians. With the aging population and age-related eye disease, we all have to become more efficient to take care of the demands that will be placed on the system. We know that the tear layer is a very complex structure. Patients who have dry eye have a marked abnormality in the quality of the tears, and all of the beneficial mediators and growth factors in the tears have disappeared, thus giving rise to the symptoms and the inflammation. Normal meibomian glands should have a patent orifice, and we should be able to express the normal olive oil-appearing material. While there are better tests out there, expressing the glands is a quick diagnostic step that should be performed on all patients with ocular surface symptoms, and it gets us thinking about diagnosing meibomian gland dysfunction (MGD). The DEWS report produced an elaborate breakdown of the different types of dry eye, but in practice, aqueous tear deficiency and evaporative dry eye due to MGD make up the vast majority of dry eyes. continued from page 3 confocal microscopy, lipid layer interferometry, and adenovirus testing. In the future, there will likely be more and more point-ofcare diagnostics with accurate answers to many of our daily clinical dilemmas. Dr. Starr is associate professor of ophthalmology and director of the refractive surgery service, ophthalmic education, and cornea, cataract and refractive surgery fellowship, Weill Cornell Medical College, New York-Presbyterian Hospital, New York. He can be contacted at cestarr@med.cornell.edu. Osmolarity has been found to be increased with decreasing flow rates, and hyperosmolarity can lead to damage of the ocular surface. It is the primary cause of discomfort associated with dry eye, and high osmolarity is associated with other inflammatory factors that we can see, such as increased MMP-9 and loss of epithelial cell-cell junctions. Researchers in the field of ocular surface disease now feel that osmolarity is a valuable marker for the disease diagnosis and severity. Osmolarity testing is not only an initial test to help diagnose ocular surface disease, it can also show whether the treatment has had an impact and if patients are improving. It is important to know patients' osmolarity levels. A physician wouldn't think of managing cholesterol without knowing the level. Additionally, we can use a new diagnostic tool, LipiView (TearScience, Morrisville, N.C.), to assess the thickness of the tear film. It uses interferometry to provide relative measure of the thickness of the lipid layer of the tear film. LipiView is another new test that assists with the diagnosis of MGD and the assessment of whether treatment is working. Markers for ocular surface disease Several markers are being evaluated in ocular surface disease. For example, lactoferrin is an important molecule in the ocular surface, and changes in the lactoferrin level are associated with ocular surface disease. It has been identified as one of the tear proteins that may be part of the innate defense of the mucosal surface. Lactoferrin levels can be determined using the TearScan MicroAssay System (Advanced Tear Diagnostics, Birmingham, Ala.). Additionally, dry eye is a multifactorial disease, and distressed epithelial cells produce elevated levels of MMP-9. Abnormal levels of MMP-9 (>40 ng/mL) have been shown to correspond with moderate to severe dry eye disease. Now, there is an in-office quick test (InflammaDry, RPS, Sarasota, Fla.) that can be done on the ocular surface to determine whether the level of MMP-9 is elevated. All of these tools will

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