Eyeworld

EW FEATURE 33 said. "However, we have a much big- ger problem on the treatment side than on the diagnostic side." Dr. Korb said if clinicians were to conduct "a complete dry eye eval- uation using the entire spectrum of tests, three separate visits would be required to differentiate what the underlying causes of the complaint might be." What is the one best "test" for diagnosing most patients? A careful and detailed patient his- tory, he said. Clinicians need to think about "the main causes of ocular surface disease overall," Dr. Holland said. "Listen to the patient. We're trying to differentiate between aqueous tear deficiency, anterior blepharitis, MGD that leads to evaporative dry eye, and ocular allergies. Those are the four big ocular surface diseases. The problem for clinicians is that symptoms may overlap among the diseases. Complaints of irritation, burning, and redness are common to all these diagnoses. We have to pay attention to the clues." One reason patient symptoms are so valuable is because "we don't have one test that's going to tell us this is dry eye and it's because of one mechanism or a bunch of mecha- nisms," Dr. Foulks said. As clinicians learn more about dry eye, a quick slit lamp exam of only the cornea is no longer enough, Dr. Holland said. "We need to carefully evaluate the lid function and tear film. We need conjunctival and corneal epithelium evaluations. We need to use vital dyes and fluo- rescein staining. Another important diagnostic tool that we often forget is to take a careful history and have a discussion about symptoms with the patient," he said. Dr. Blackie also opts for "history and symptomatology first." Because physicians have limited time with the patient—10-20 minutes in the chair at most, she said—"never toss out symptoms because some of the clinical signs may not match. That doesn't mean to pick one over the other—always consider both signs and symptoms." Identifying those with severe disease is often much easier than identifying those in earlier stages, Dr. Lemp said. For instance, Schirmer's test scores are likely nor- mal in people in the early to moder- ate stages; the test measures lacrimal damage, not meibomian gland dam- age, so it will not assess evaporative dry eye accurately, he said. "The bottom line—be a doctor. Listen to the patient. You cannot take the patient out of this diagnos- tic equation," he said. If patients have "severe surface disease but are not complaining, that indicates chronicity and puts them into a much more severe cate- gory. They've lost corneal sensation and don't appreciate the dysfunc- tion of the tear any longer," Dr. Foulks said. The type of dry eye will dictate whether Dr. Foulks first rec- ommends an artificial tear with a lipid component (for predominantly evaporative dry eye) or a tear that increases the volume alone or that protects against elevated osmolarity. There remains a "huge need for objective measurement with an un- biased measure of tear film quality and status," Dr. Starr said. "We've known for years that increased tear osmolarity is an important diagnos- tic finding," but it was too cumber- some in the past to evaluate. A new diagnostic tool, the Tear- Lab osmolarity test, "is probably the most reliable measure of determin- ing if there is dry eye, but you need at least one additional test to deter- mine what kind of dry eye," Dr. Foulks said. "In terms of patient acceptance, they like the osmolarity test because it's less invasive and gives them a number they can wrap their mind around. Osmolarity has a baseline of 308—above that and you've got dry eye, below that and you don't," Dr. Lemp said. For Dr. Foulks, osmolarity is also a measure to ensure the treatment regimen is working. "When patients report they feel better, osmolarity can confirm their eyes are improv- ing clinically, as the number goes down as well. If I have a patient who doesn't notice a lot of improvement but the osmolarity is decreasing, then I know there's evidence we're on the right treatment track." Summarized Dr. Lemp: The tear film osmolarity test "parallels disease severity. Osmolarity is still variable, but it's the least variable of any of the tests we currently have." Another potential diagnostic test is the InflammaDry (Rapid Pathogen Screening, Sarasota, Fla.), which detects the matrix metallo- proteinase 9 (MMP-9) protein. In- creased levels of MMP-9 have been previously reported in the tear fluid of those with dry eye. TearLab also has a platform that may potentially be able to measure lactoferrin, but does not yet have a test, Dr. Foulks said. According to Dr. Holland, the TearScience LipiFlow "is positioned around the lower lid and heats up the meibomian glands to a specific temperature. In clinical trials it showed a better function of the mei- bomian glands and better flow of meibum, in turn creating a better quality tear film." The device is still under investigation in the U.S., he added. Evaluating the unknown One problem for those investigating dry eye is "we don't know what we don't know," Dr. Korb said. For in- stance, until recently the role of the eyelid and lid wiper in dry eye was unknown, but now about 80% of those with dry eye also have some level of lid wiper epitheliopathy, said Drs. Korb and Blackie. Although inflammation is now a given for those with dry eye, re- searchers have not yet been able to sufficiently identify all the inflam- matory cytokines in tears, Dr. Lemp said. Conversely, a drug such as topi- cal azithromycin (AzaSite, Inspire Pharmaceuticals, Durham, N.C.) has shown great promise in treating MGD, "but we're still waiting for FDA approval for that indication," February 2011 April 2011 OCULAR SURFACE Lissamine green staining helps clarify the severity of the ocular surface Poor tear break-up time is also indicative of increased dry eye severity Source: Gary Foulks, M.D. continued on page 34 032-047 Feature_EW April 2011-DL_Layout 1 4/10/11 8:00 AM Page 33

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