dry eye dx and tx
The New Dry Eye, Part 1: Patient Symptoms
BY KELLY K. NICHOLS, OD, MPH, PHD
In April 2007, the Report of the International Dry Eye Workshop (DEWS) published in the journal The Ocular Surface. The complete report will most likely be the single most important full-scope document related to dry eye disease for the upcoming decade.
Dry Eye Defined
The report established a new definition of dry eye. This first of three discussions of the new dry eye definition will focus on the aspect of dry eye disease that's arguably most important to patients and clinicians alike: patient-reported symptoms (Table 1). While symptoms have always been the backbone of the dry eye diagnosis, changes to the wording have been made related to symptoms in the new definition.
Symptoms of Discomfort
Over the last 10 years we've significantly expanded our understanding of the epidemiology of dry eye, including the symptoms most frequently reported by dry eye patients. Discomfort, irritation and dryness are general terms that many dry eye patients use to describe the sensation of the ocular surface.
In addition to these terms, many patients report ocular itching, which could be a learned term that patients generalize to the ocular surface or it could result from an associated mast cell-histamine-inflammatory cascade response. We continue to learn about the relationship between allergy and dry eye, as well as about the link between dry eye and other ocular surface diseases such as meibomian gland disease.
Symptoms of Visual Disturbance
Clinicians are well aware that patients who have dry eye are sensitive to fluctuations in clear vision. When asked, patients report that they stop what they're doing to close their eyes, and they report an increase in blinking especially toward the end of the day. Both of these activities are done in an effort to maintain a clear visual image.
It's nice to see that visual disturbance is now recognized as part of the symptomatology for dry eye. What is unclear is how we can objectively measure visual disturbance, including its impact on quality of life and daily activities. We'll continue to see advances in this area in the future, including the use of visual wavefront and interferometry-type technology.
In late 2006, the report of an international task force using the Delphi technique published in Cornea. This group of expert clinicians determined that dry eye should be termed "dysfunctional tear syndrome." While this term may reflect a universal component of the disorder, to date it has yet to be widely accepted.
However, the term tear instability has been added to the definition of dry eye, and like the Delphi group, many researchers believe that tear instability is a key component in the development of dry eye symptoms. Treatments tailored to increase tear stability may have the preventive effect of limiting the vicious cycle of dry eye disease.
The complete DEWS reports are available in free PDF format at www.tearfilm.org. CLS
Dr. Nichols is an associate professor at The Ohio State University College of Optometry in the area of dry eye research.