Issue: April 2008
The Definition & Classification of Dry
Guidelines from the 2007 International Dry Eye
BY MICHAEL A. LEMP, M. D. AND GARY N. FOULK S, M. D.,
The diagnosis of dry eye and its treatment has long been approached somewhat
subjectively. Even more so, it's an ocular ailment that hasn't always been treated with
enough gravity given the impact this disease can have on the people who live with it.
We believe this will start to change with the publication of the DEWS Report. The
2007 International Dry Eye Workshop, sponsored by the Tear Film and Ocular
Surface Society [TFOS] was created to provide an evidence-based critical review and
summary of the classification, epidemiology, diagnosis, techniques of basic and
clinical research, and management of dry eye disease.
This report, recently published in The Ocular Surface,1 provides an encyclopaedic,
evidence-based review of dry eye disease. The report was a product of a team of
international experts who spent three years appraising the present state of knowledge
for dry eye disease and the methods used to evaluate, diagnose and manage the
This article summarizes the section of the report addressing the definition and
classification of dry eye disease. Members of the DEWS Definition and Classification
Subcommittee developed a contemporary definition of dry eye disease and a three-
part classification system based on etiology, causative mechanisms and disease
severity. The guidelines described are not intended to override the clinical assessment
and judgement of an expert clinician in individual cases, but they should prove helpful
in the conduct of clinical practice and research.
Definition of Dry Eye Disease
The committee began by reviewing the following definition of dry eye disease that
was adopted by the 1995 National Eye Institute (NEI)/Industry Dry Eye Workshop:
Dry eye is a disorder of the tear film due to tear deficiency or excessive evaporation,
which causes damage to the interpalpebral ocular surface and is associated with
symptoms of ocular discomfort.
The group decided to update this definition to take account of new knowledge about
the roles of tear hyperosmolarity and ocular surface inflammation in dry eye, and the
effects of dry eye on visual function. The following updated definition was produced:
Dry eye is a multifactorial disease of the tears and ocular surface that results in
symptoms of discomfort, visual disturbance, and tear film instability with potential
instability leading to ocular surface damage. Since both aqueous tear deficiency and
increased evaporative tear loss occur in most cases of dry eye disease and are linked
by common pathogenetic mechanisms, expert clinicians are increasingly basing
treatment decisions on an assessment of severity rather than discrete deficiencies.
The group believed that a classification of disease based on severity would be of
considerable value in clinical practice, particularly in terms of guiding therapeutic
decisions. This third component of our classification system was based on the severity
grading scheme included in the Delphi Panel report (Table 1).
By establishing these definitions and classification of dry eye disease, we believe
clinicians will be better able to determine the level of DED, as well as the best
treatment course for their patients. OM
1. 2007 Report of the International Dry Eye Workshop (DEWS). The Ocular
Surface. 2007;5:65-204. For a full copy of the DEWS report, please visit the
TFOS website: www.tfos.org.
2. Behrens, A, Doyle, J, Stern, L, et al. Dysfunctional Tear Syndrome: A Delphi
Approach to Treatment Recommendations. Cornea. 25:900-907, Sept. 2006.
Michael A. Lemp, M.D. is clinical professor of ophthalmology at
Georgetown and George Washington Universities and chief medical
officer of OcuSense, Inc. He can be reached at (202) 338-6424 or email
him at email@example.com.
Gary N. Foulks, M.D. is professor of ophthalmology at the Kentucky
Lions Eye Center, University of Louisville. He may be reached at 502-
852-6150 or emailed at firstname.lastname@example.org.
Neither author has any financial arrangement with any of the products or
techniques mentioned in this article.