discovering dry eye
Redefining Dry Eye
BY KELLY K. NICHOLS, OD, MPH, PHD
The fourth International Conference on the Lacrimal Gland, Tear Film, Ocular Surface and Dry Eye Syndromes: Basic Science and Clinical Relevance took place this past November in Fajardo, Puerto Rico. More than 400 scientists, physicians, industry representatives and participants from around the world attended the meeting and contributed to the advancement of the field.
Before the meeting, a smaller group of approximately 45 participants met for the Dry Eye Workshop with the intent of revisiting the 1995 National Eye Institute/Industry report on Clinical Trials in Dry Eye by Lemp et al. Both of these meetings highlighted recent progress made in dry eye both clinically and in basic research.
Considering a New Definition
One of the goals of the dry eye workshop was to review and revise the existing dry eye definition, which states: Dry eye is a disorder of decreased tear production or increased evaporation characterized by symptoms and surface damage. Some of the leading issues that we need to address in the definition include the following concepts:
- Dry eye is multifactorial.
- Dry eye is a disorder of tear dysfunction.
- Dry eye symptoms include discomfort and associated visual disturbance.
- Inflammation plays a role in dry eye.
- Surface damage may not be clinically detectable.
Final revisions to the definition may include some or all of these issues. We can expect the final version following the Dry Eye Workshop at the 2005 Association for Research in Vision and Ophthalmology meeting.
A report by Schaumberg et al at the meeting indicated that approximately 6.4 million women and 2.7 million men (range: seven million to 12.6 million total individuals) in the United States have moderate to severe dry eye based on severe symptoms and/or a dry eye diagnosis. Of those, many use artificial tears and report that dry eye symptoms limit some aspect of their performance (such as reading or driving). Clearly, a need exists for more sensitive and specific tests and novel therapies.
Osmolality: The Gold Standard?
Ten years ago, researchers debated the importance of osmolality in the pathogenesis of dry eye, and the argument continues today. Developing and measuring tear film osmolality has proven a significant challenge over the last decade because of a lack of clinically available instrumentation. Two companies (Advanced Instruments and OcuSense) are currently developing commercially available nanoliter osmometers to measure osmolality. Available instrumentation should help to clear up the mystery behind this diagnostic test.
Diagnosis in the Future
Reports and presentations at the meeting highlighted technology advances that are expected to change the way we manage patients who have ocular surface disease. Many of these "tests" are still in the development phase; however, we hope that the technology in development will become available for clinical care sooner rather than later. Examples presented include: interferometry techniques, wavefront technology, advanced topographical imaging, confocal microscopy, florophotometry and digital video imagery (such as fluorescein tear break-up, infrared meibography and lissamine green conjunctival staining).
In advancing our understanding of the etiology of ocular surface disease, advancing clinical care is on the horizon.
Dr. Nichols is assistant professor of clinical optometry at The Ohio State University College of Optometry in the area of dry eye research.