EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/78716
94 EW SECONDARY FEATURE February 2011 Dry eye March 2012 Diagnosing dry eye by Jena Passut EyeWorld Staff Writer E ven as our current issue of EyeWorld highlights impres- sive new technologies for the refractive cataract surgeon, we cannot neglect the most important re- fractive elements of the optical system— the ocular surface and tear film. Surgeons entering the expanding realm of refractive cataract surgery would ignore ocular surface co-morbidities to the detriment of their patients and themselves, since un- derdiagnosed issues like tear film abnor- malities, corresponding ocular surface diseases, and lid margin disease are pre- dictive of poor outcomes and unsatisfied patients. In screening candidates for refractive cataract surgery, several new technologies take a closer look than ever before at the biochemical and biomechanical features of the tear film. Rapid in-office screening for matrix metalloproteinases (MMPs) may become a mainstream part of the pre-op evaluation and selection of patients desir- ing premium IOLs. In my own practice, I am often startled by the normalizing effect a superficial keratectomy and amniotic membrane graft has on the once-distorted pre-op biometry of a cornea affected by basement membrane dystrophy or nodular degeneration, both conditions highly corre- lated with the presence of certain MMPs. Lipid layer analysis and treatment of mei- bomian gland dysfunction should be inte- grated into the routine pre-op refractive cataract evaluation. The visual effect of femtosecond technologies—to improve the precision of astigmatism correction, reduce effective phaco times, and increase consistency of the size and shape of the capsulorhexis and therefore effective lens position—are only as good as the condition of the ocular surface. In the words of a great mentor, anything we address with patients before surgery is an expectation; anything we tell them after surgery is a complication. Our ability to address ocular surface issues prior to refractive cataract surgery will prove critical to our ability to produce extraordinary results and extraordinarily happy patients. Neel Desai, M.D., refractive editorial board member cially available, osmolarity testing with the TearLab Osmolarity System (TearLab Corp., San Diego) is readily available to test for subclinical dry eye. Osmolarity is a good dry eye marker, but it won't tell a clinician what type of dry eye the patient has, Dr. Donnenfeld noted. "Tear film osmolarity has a good linear correlation with severity, as has been shown now in several stud- ies," Dr. O'Brien said. An irregular topography reading also points to dry eye and is a key test, Dr. Donnenfeld said. "When you see drop out on a topography, it means that the tear film has been disrupted," he ex- plained. Rainbow colors in the tear film indicate that it is rich with lipids that are required to keep the aqueous portion of the tears from evaporating too quickly Source: TearScience Latest tools show promise for identifying dry eye and meibomian gland disease A case of dry eye disease, however mild, can wreak havoc on a surgical or treatment outcome. Inventors and companies are continuing to establish ways for clinicians to pre-operatively diag- nose the pervasive disorder, which was defined by the Dry Eye Work- shop Study Group (DEWS) in 2007 as a multifactorial disease of the ocular surface that includes an element of inflammation and is ac- companied by increased osmolarity. Practitioners now are looking beyond clinical presentations such as Schirmer's test, tear break-up times, or conjunctival/corneal stain- ing to biomechanical markers to di- agnose ocular surface dysfunctions. Testing for MMP-9 The RPS InflammaDry Detector (Rapid Pathogen Screening, Sarasota, Fla.) is a rapid in-office test that detects elevated levels of matrix metalloproteinase-9 (MMP-9), an inflammatory marker. The device, which was recently launched in Europe and Asia and was granted a Medical Device License by Health Canada, delivers results taken from a small sample of human tears in 10 minutes. RPS noted the device has a clini- cal sensitivity of 85% and a speci- ficity of 94%. "These are enzymes that are pro- duced by stressed epithelial cells on the ocular surface," said Terrence O'Brien, M.D., professor of ophthal- mology, Bascom Palmer Eye Insti- tute, University of Miami Miller School of Medicine, who spoke about the test at the 2012 Hawaiian Eye meeting in Maui. "[The test is] easy to use and gives an immediate result, and we can incorporate this into our clinical practices in order to make a diagnosis and, more impor- tantly, to institute effective treat- ments, especially treatments that would be aimed at reducing inflam- mation on the ocular surface." Dr. O'Brien said he expects the device to become commercially available in the U.S. in early spring. Eric D. Donnenfeld, M.D., co-chairman, Cornea, Nassau University Medical Center, East Meadow, N.Y., called MMP-9 testing "exceptionally interesting." "I think it's going to change the way dry eye is managed," he said. "Dry eye is the most difficult diag- nosis to make clinically because every patient is so variable. Some patients can be extremely sympto- matic, some not. The future is going to be using point-of-care tests in your office." In the meantime Until an MMP-9 device is commer- Looking at the lipid layer Donald Smallman, M.D., adjunct assistant professor, Queens Univer- sity, Kingston, Ontario, and medical director, Kingston Eye Institute, has established a dry eye clinic in his practice. There, each patient fills out a screening questionnaire. "Because dry eye is such a com- mon issue that plays a role in other eye diseases, many of our patients coming in for other issues will also have dry eye as a feature of their complaints," Dr. Smallman said. If a slit lamp examination with dilating eye drops confirms suspi- cion of dry eye, Dr. Smallman brings patients back another day to be ex- amined with the LipiView OSI (TearScience, Morrisville, N.C.). The LipiView uses spectral inter- ferometry, a spatially modulated light source that allows removal of unwanted background images and stray light, to analyze the patient's lipid layer of tear film, as well as his or her blinking. "It gives a lot of information above and beyond just the lipid layer of the tears," Dr. Smallman said. "That's very important because it allows us to determine if a patient is suffering from evaporative dry eye because the absence or low levels of lipids in the tear film is associated with certain types of dry eye prob- lems. It also allows us to target cer- tain treatments to the meibomian glands specifically, as opposed to providing drops or supplements that will restore the aqueous layer. I feel like this is going to be a real boon for dry eye assessment."