Eyeworld

EW CORNEA 62 February 2016 diagnostic tests are indirect measure- ments. The TearLab osmolarity test, for example, measures impedance, from which osmolarity is imputed from an algorithm. The higher the osmolarity, the more likely the patient has inflammation due to dry eye. The device uses 308 mOsmol/L as its cutoff. Higher than 308 mOsmol/L is considered an abnormal level. An asymmetric result also may indicate tear quality issues." Osmolarity does not distin- guish between the types of dry eye. "After you've done the test, the patient has a number, but the clini- cian still doesn't know which med- ication or therapy might be best for that particular patient," he added. The lactoferrin test, however, does offer some differentiation. "High lactoferrin in the presence of normal to high tear volume there's value to that," Dr. Latkany said. The difficult-to-diagnose pa- tients may be where these tests are most useful, Dr. Pflugfelder said. "These are patients who have a lot of symptoms and not much in the way of objective findings. Maybe they'll have a rapid tear break-up time (TBUT) and normal osmolarity. That's where I'm scratching my head and wondering why this patient is so symptomatic," he said. Dr. de Luise added, "It would be very helpful if we had a validated, reproducible test, where we could use the results of this testing to interpret the type of dry eye, either EDE or ADDE. We could then go to an algorithm that would allow us to treat that particular type of dry eye appropriately, without misdiagnoses or incorrect treatment strategies." For example, the one currently marketed dry eye treatment "doesn't seem to work as well for meibomian gland dysfunction or EDE as it does for true ADDE," Dr. de Luise said. It can be equally frustrating for the clinician who cannot make a definitive diagnosis, Dr. Pflugfelder said. "We can define a population of people that has normal aque- ous tear production/volume and a rapid TBUT, so they definitely have something wrong with their tears, but I can't say exactly what it is. It's probably lipid deficiency, but I don't know that for sure," Dr. Pflugfelder said. An "evolving" disease state— conjunctivochalasis or redundant conjunctiva "that basically obliter- ates their tear meniscus—is a "huge problem in our aging population," Dr. Pflugfelder said. Some of the newer tests in addition to clinical signs can help him identify that group of patients simply by process of elimination. Specificity and sensitivity Specificity and sensitivity are tradi- tionally key metrics when evaluating diagnostic tools, Dr. de Luise said. None of the currently marketed devices have 100% specificity or sen- sitivity, although some have a high 90s rating in specificity (see table). Then there is the issue of break- points. For example, the result of the InflammaDry test "doesn't provide a quantitative numerical result of the MMP-9 level. Rather, it provides a qualitative positive or a negative re- sult implied from a breakpoint of 40 ng/ml. MMP-9 levels greater than 40 ng/ml will display a positive result," Dr. de Luise said. "Some of the other Running continued from page 60 Name of test What it evaluates CPT code Independently verified? Manufacturer/marketer InflammaDry Detects MMP-9, an inflammatory marker associated with dry eye 83516, "immunoassay for analyte other than infectious agent antibody or infectious agent antigen; qualitative or semi-quantitative, multiple step method" No. Data on file with RPS claims 81% positive agreement/sensitivity; 98% negative agreement/specificity Rapid Pathogen Screening (RPS) LipiView/LipiFlow Imaging device; interferometer measures the absolute thickness of the tear film lipid layer LipiView 1 : Category III CPT code 0330T (Tear film imaging, unilateral or bilateral, with interpretation and report) LipiFlow 1 : Category III CPT code 0207T (Evacuation of meibo- mian glands, automated, using heat and intermittent pressure, unilateral) to report this procedure No. For a cut-off value of ≤75-nm lipid layer thickness, a sensitivity of 65.8% and a specificity of 63.4% for the detection of a meibomian gland dysfunction. For a cut-off value of ≤60, the sensitivity was 47.9%, and the specificity was 90.2% 2 TearScience Sjö test Combines 4 traditional biomarkers with 3 novel, propriety biomarkers to detect Sjögren's syndrome early in its disease course 36416 (finger stick) + CPT codes for lab tests run No. Company claims 89% cumulative sensitivity and 78.2% cumulative specificity Bausch + Lomb TearLab osmolarity test Tear assay that determines the osmolarity level in each eye 83861, Microfluidic analysis utilizing an integrated collection and analysis device, tear osmolarity 3 No. Per the company: "osmolarity was found to have 88% specificity, 75% sensitivity in mild/moderate disease and 95% sensitivity in severe disease at a diagnostic cutoff of 308 mOsms/L" TearLab TearScan/TearScan Compact MicroAssay Detects levels of lactoferrin and IgE tears 83520, "Immunoassay for analyte other than infectious agent antibody or infectious agent antigen; quantitative, not otherwise specified" Unclear. Sensitivity: 83% Specificity: 98% Advanced Tear Diagnostics Notes 1. Category III CPT codes are generally non-covered. LipiView and LipiFlow are categorized as "experimental" or "investigational" by other 3rd party payers (per Corcoran Consulting Group, www.corcoranccg.com/products/faqs/lipiview-dmi-lipiflow/) 2. Finis D, et al. Evaluation of lipid layer thickness measurement of the tear film as a diagnostic tool for meibomian gland dysfunction. Cornea. 2013;32(12):1549–53. 3. 83861 is paid from the Medicare Clinical Laboratory Fee Schedule (CLFS), not the Physician Fee Schedule. 83861 may be performed by a lab certified under the Clinical Laboratory Improvement Act (CLIA), including a lab that has a CLIA Waiver certificate

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