Dr. Gilbard is Clinical Assistant Professor, Harvard Medical School, Boston, Massachusetts; Director, Dry Eye and Ocular Surface Disease
Clinic, Tufts New England Eye Center, Boston.
Disclosure: The author is Founder, CEO, and Chief Scientific Officer, Advanced Vision Research, Inc., Woburn, Massachusetts.
ABSTRACT
Dry eye is the most common cause for chronic eye irritation in the patient over age 50 years and is multifactorial in etiology.
Whatever the etiology, the final common pathway is loss of water from the tear film, with an increase in tear film osmolarity.
Patients with dry eye experience sandy-gritty irritation, dryness, burning, or increased awareness of their eyes that gets
worse as the day goes on. These patients need to be distinguished from patients with posterior blepharitis, or meibomitis,
in which similar symptoms are worse on eye opening. Dry eye treatment includes strategies to lower tear film osmolarity and
treat associated eyelid disease. The effectiveness of available treatments often leaves something to be desired. This condition
may be severely disabling in advanced cases. Gilbard JP. Dry eye and blepharitis: Approaching the patient with chronic eye irritation. Geriatrics. 2009;64(6):22-26.
Key words: blepharitis, dry eye, meibomitis, tear film osmolarity
Drugs discussed: doxycycline
Dry eye is an important problem in the office setting because it may cause significant patient morbidity and because it is
so common. For example, a US population-based study estimated that 7.8% of women over age 50 years and 9.8% of women over
age 75 years have dry eye.1 If we look at the larger category of chronic eye irritation and include posterior blepharitis, or meibomitis, the other
common cause for chronic eye irritation, the prevalence rises even higher.
The tear film is made up of 3 layers: a layer consisting of the mucus produced by goblet cells in the conjunctiva and the
glycoproteins on the corneal and conjunctival cell surface membranes; a watery layer produced by the lacrimal gland in the
orbit and the accessory lacrimal glands in the conjunctival fornices; and an oil layer, produced by specialized oil glands
in the eyelids, meibomian glands, that coat the tear film and retard evaporation. Most patients presenting to the office with
chronic eye irritation will ultimately be diagnosed with either dry eye or posterior blepharitis (meibomitis).
Dry eye is caused by any condition that decreases tear production or increases tear evaporation sufficiently to result in
a loss of water from the tear film and an increase in tear film osmolarity.2 Tear production can be decreased by lacrimal gland disease, as seen in Sjögren's syndrome, or by any condition that decreases
corneal sensation. Included among the more common causes for decreased corneal sensation are diabetes mellitus, laser-assisted
in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) procedures that interrupt or ablate corneal nerves, and
long-term hard contact lens wear. About 57% of patients with type 1 diabetes and 70% of those with type 2 diabetes have been
reported to have dry eye.3
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