NOV 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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5 Identifying fundamentals of how unique diagnostic tools are assessing key information in the tear film by Marguerite McDonald, MD I n addition to the point-of-service laboratory tests that are based on the osmolarity of the tear film, there are new and unique diagnostic tools that use imaging to help assess key information about the tear film. The new tests include white light interferometry to assess the thickness of the lipid layer of the tears, automated tear film height measurement, automated and noninvasive tear film breakup time, assessment of the tear film viscosity using automated tracking of particle movement, meibography with image analysis, automated detection of bulbar and ciliary redness, optical coherence tomography (OCT) to measure tear meniscus height, and lid parallel conjunctival folds. LipiFlow/LipiView The system from TearScience (Morrisville, N.C.) includes LipiFlow, which is the treatment aspect of the technology; LipiView, which is the diagnostic aspect; and the meibomian gland evaluator for applying a standard amount of pressure to the glands of the lower lid. There is an assessment of the thickness of the lipid layer based on white light interferometry. The thicker the layer of oil, the more colors that are visible. So the The R-Scan automatically detects bulbar redness. way the light diffracts through it and the number of colors that can be seen provide extremely accurate information about the thickness of the lipid layer. Based on this principle, LipiView uses advanced interferometric technology to capture, archive, manipulate, and store detailed digital images of the tear film's lipid layer. Interferometric color unit (ICU) statistics are calculated on a frame-byframe basis and are plotted for approximately 1 billion data points per eye. The results are then displayed and are available for printout. LipiView provides an absolute measure of the thickness of the lipid layer of the tear film, and it provides a ratio of partial blinks to complete blinks for the duration of the exam. The LipiView report can be used for assessment, patient education, monitoring response, prognosticating, and planning treatment. 14 to 16 days after initial symptoms, thus leading to the outbreaks that are often seen. Prompt diagnosis is imperative to prevent the spread of this infection. AdenoPlus (Nicox, Sophia Antipolis, France) aids in the rapid differential diagnosis of acute conjunctivitis. It detects adenovirus with 90% sensitivity and 96% specificity, and it takes less than two minutes to complete the test and provides results in 10 minutes or less. This has the potential to significantly reduce the epidemics we now see with adenovirus. • Assess hyperosmolarity on tear film stability • Determine meibomian gland dysfunction • Identify MMP-9 and lactoferrin for the severity and type of dry eye disease • Detect adenoviral conjunctivitis among acute conjunctivitis patients • Better match the treatment of dry eye and conjunctivitis to the specific patient's condition continued on page 6 continued from page 4 assist in making a correct diagnosis more rapidly and make us better and more efficient clinicians. Adenovirus and the tear film Adenoviral antigens can be found in the tear film, and adenovirus is the most frequent cause of infectious conjunctivitis. Additionally, it accounts for up to 90% of all viral conjunctivitis. Unfortunately, eyecare providers, including cornea specialists, are not very good at diagnosing adenovirus. In fact, only 30% to 35% of the patients seen by corneal specialists for a diagnosis of adenovirus actually had adenovirus. In other words, approximately 65% of the time, the patient had something else. Adenovirus can live on inanimate surfaces for four to five weeks. It can shed for Point-of-care diagnostics In conclusion, point-of-care advanced tear film diagnostics will assist clinicians to be better and more efficient. New tests have the ability to do the following: Dr. Holland is professor of ophthalmology, University of Cincinnati, and director of cornea and external disease, Cincinnati Eye Institute. He can be contacted at eholland@holprovision.com.

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