EyeWorld Asia-Pacific June 2013 Issue

58 EWAP DEVICES June 2013 Osmolarity, inflammatory markers, lipid layers, and topography—each has its pros and cons in diagnosing dry eye C linical signs and subjective symptoms of dry eye often do not correlate, making it difficult at best for physicians to diagnose the disorder. What is now known is that “most dry eye is evaporative, or at least has a significant evaporative component, and somewhere around 86-87% of all dry eye patients have the evaporative form,” said Marguerite McDonald, MD , in private practice, Ophthalmic Consultants of Long Island, Lynbrook, NY, USA, and clinical professor of ophthalmology, Tulane University School of Medicine, New Orleans, La., USA. (The other subtype is aqueous deficient dry eye.) It is also well established now that “ocular surface inflammation is a pathophysiologic variable in the definition of dry eye,” said Christopher E. Starr, MD , associate professor of ophthalmology, director of the refractive surgery service, director of the cornea, cataract, and refractive surgery fellowship, and director of ophthalmic education, Weill Cornell Medical College, New York, NY, USA. In terms of actually diagnosing the disease, some tests (such as Schirmer’s) are more than a 100 years old, said Michael A. Lemp, MD , clinical professor of ophthalmology, Georgetown University and George Washington University, Washington, DC, and chief medical officer, TearLab Corp, San Diego, Calif., USA. “The most important Quantitative metrics for dry eye by Michelle Dalton EyeWorld Contributing Writer determinant of dry eye remains the patient,” said John D. Sheppard, MD , president, Virginia Eye Consultants, Norfolk, Va., USA, and clinical director, Thomas R. Lee Center for Ocular Pharmacology, Eastern Virginia Medical School, Norfolk, Va., USA. “If the patient has signs, symptoms, and visual disturbances, it doesn’t matter what the quantities are. The most important piece of this picture is the informed, highly concerned eyecare specialist who synthesizes all the data and comes up with a plan for the patient that makes sense.” Before the plethora of diagnostic tools became available, Dr. Starr said most corneal specialists thought diagnosing dry eye was relatively simple. “That’s not the case. It’s not easy to make an accurate diagnosis with just your clinical acumen in all cases. But having more objective point-of-care tests available that are accurate and easy to use has moved us rapidly forward,” Dr. Starr said. Too many practitioners rely on the Ocular Surface Disease Index, but patients may be in the office on a “good” day, or after a return from a high humidity (or low humidity) environment, skewing the subjective opinions, Drs. Lemp and Sheppard both said. Corneal sensation is another modality that is more commonly employed in clinical research than in clinical practice, Dr. Sheppard said. Lactoferrin “can also act as a marker of either inflammation or tear solution,” he said, but using lactoferrin as a test for dry eye is still in its infancy. “While the jury is not in on this one, we are all looking forward to gaining experience there,” Dr. Sheppard said. “Ocular surface treatment and dry eye The TearLab Osmolarity Test is used to measure the osmolarity of human tears. Source: TearLab The LipiFlow Thermal Pulsation System treats the primary cause of evaporative dry eye. Source: TearScience The Keratograph combines keratometric and corneal topography measurement with high resolution of the cornea. Source: Oculus