Eyeworld

APR 2011

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

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EW FEATURE 32 by Michelle Dalton EyeWorld Contributing Editor Diagnosing dry eye Clinical signs and patient-reported symptoms may not correlate; patient symptoms must take precedence O ne of the most common reasons people visit eye- care specialists is due to complaints of dry eye, yet specialists and those in general practice believe the numbers are wildly underestimated. "In my practice, 40-50% will have some form or complaint of oc- ular surface dysfunction," said Christopher E. Starr, M.D., assistant professor of ophthalmology, and di- rector, cornea, cataract, and refrac- tive surgery fellowship and service, Weill Cornell Medical College, New York. According to Caroline Blackie, O.D., Ph.D., clinical research scien- tist, Korb Associates, Boston, and TearScience, Morrisville, N.C., in the winter months (January-March) "somewhere between 35% and 40% of patients have some complaint re- lated to dryness in our general prac- tice. In the summer months, it's somewhat less—maybe closer to 20- 25% of people who come in without referrals." While the incidence of dry eye might fluctuate depending on geog- raphy, "there's an understanding of what constitutes dry eye that's be- ginning to change as well," said Michael A. Lemp, M.D., clinical professor of ophthalmology, George- town University, and George Wash- ington University, Washington, D.C., and chief medical officer, TearLab, San Diego. As defined by the Dry Eye Workshop Study Group (DEWS) in 2007, dry eye is a multi- factorial disease of the ocular surface that includes an element of inflam- mation; it is also accompanied by increased osmolarity. Perhaps as a re- sult of the DEWS report, clinicians are now more aware of dry eye and are actively looking to treat it. Not only is the percentage of pa- tients who present with primary complaints of dry eye much higher than some estimates suggest, "there is a group of patients who come in for some other complaint but have significant ocular surface disease as a secondary diagnosis," said Edward J. Holland, M.D., professor of oph- thalmology, University of Cincin- nati, and director of cornea, Cincinnati Eye Institute. For in- stance, Dr. Holland said, when ana- lyzing his cataract population, the incidence of meibomian gland dys- function (MGD) with evaporative dry eye is "very high. So when peo- ple complain of decreased vision and you're thinking about cataract surgery, you may inadvertently over- look an important secondary diag- nosis of MGD. Although that's not what the patient came in for, it will affect the surgical outcomes of ante- rior segment surgery." The number of people who come into a practice without think- ing they have any dry eye compo- nent "is very high as well. But a significant number of those people will have some kind of dry eye," said Donald R. Korb, O.D., founder, Korb Associates, and co-founder, Tear- Science. Compounding the issue is the fact that lid margin disease is "offi- cially considered dry eye, but the problem is primarily lid margin dis- ease with evaporative dry eye," said Gary Foulks, M.D., emeritus profes- sor of ophthalmology, department of ophthalmology and visual sci- ences, University of Louisville School of Medicine, Ky. When people do present with dry eye, "mild dry eye can have se- vere symptoms, and people with severe dry eye can report no symp- toms," Dr. Starr said. Chronic severe dry eye can cause damage to the corneal nerves; "the nerves become relatively desensitized with a reduc- tion in corneal sensation—hence less pain and fewer complaints—but the surface looks like a complete mess at the slit lamp." An individ- ual's pain tolerance will also factor into the magnitude of complaints, Dr. Starr added. "There are patients with 20/70 vision who have no complaints or reduction in daily functioning, and then there are those with 20/25 vi- sion who are miserable; similarly, the discordance between dry eye signs and symptoms in some pa- tients is related to an individual's tolerance level and personality," he said. Lifestyle choices A decade ago, clinicians expected those in the computer field to have increased levels of dry eye compared to their counterparts, Dr. Blackie said, with a "marked difference" be- tween software engineers and oth- ers. With the influx of computer games, smartphones, and online gaming, however, "there's an ex- panding age range. As few as 15 years ago, we rarely heard of chil- dren with dry eye complaints. For risk factors, lifestyle is a tremen- dously important factor; age and gender are not as definitive as they used to be," she said. People who predominantly use computers for hours at a time have reduced blink rates, which will exac- erbate any ongoing dry eye com- plaints, Dr. Starr said. "When you're working on a computer, your blink rate decreases, sometimes by 50%, leading to in- creased tear evaporation, surface dryness, and all the typical symp- toms of dysfunctional tear syn- drome," he said. Add forced air systems to the mix, and computer vision syndrome becomes even worse, leading to dryness, accom- modative fatigue, and headaches, Dr. Starr said. "The pervasive presence of the computer in our daily lives is the culprit for numerous complaints," he said. "Patients who are otherwise healthy present with increased evap- orative dry eye because of the de- creased blink rate and high inter- blink fluctuations throughout the day. Often when these same people go home and relax, the blink rate re- turns to normal and the symptoms dissipate." These kinds of "transient" dry eye patients may be managed with artificial tears and simple lifestyle modifications, he said. Diagnostic dilemmas As recently as a decade ago, "every- one thought dry eye was solely aqueous deficiency and we treated it with artificial tears," Dr. Foulks said. Now clinicians are aware of MGD and evaporative dry eye, and "most cases are a hybrid type of dry eye that's both aqueous deficient with MGD and/or evaporative," he said. Chronic dry eye patients can be frustrating, and diagnosis of the cor- rect ocular surface disease can some- times be challenging, Dr. Holland February 2011 OCULAR SURFACE April 2011 An eye with a poor tear film surface Source: Gary Foulks, M.D. AT A GLANCE • Dry eye complaints remain a leading cause of patient visits to eyecare professionals • Clinical signs may not match patient-reported symptoms in early disease. Listening to a patient's complaints remains the most effective measure for qualifying dry eye disease • Tear film osmolarity tests can identify those with dry eye but cannot differentiate between the subtypes • Evaluating/treating the eyelids will help treat the tear surface 032-047 Feature_EW April 2011-DL_Layout 1 4/10/11 8:00 AM Page 32

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