Chronic Dry Eye Information:

Causes of Chronic Dry Eye

Chronic Dry Eye often is the result of a dysfunction in the lacrimal functional unit that helps produce a person's natural tears.

Click here for an interactive demonstration of the difference between tears produced by a patient with Chronic Dry Eye and tears produced by a healthy person

The lacrimal functional unit includes the lacrimal glands, meibomian glands, conjunctiva, and interconnecting innervation. Lacrimal dysfunction often means production of fewer tears than are needed to keep the ocular surface protected; moreover, the tears that are produced don’t contain all the nutrients that natural, healthy tears normally do.1 In other cases of Chronic Dry Eye, there's not enough oil in the tear film covering the ocular surface, making tears evaporate faster and leaving dry areas on the cornea.

Onset of lacrimal gland dysfunction, and ultimately Chronic Dry Eye, can be caused by hormonal changes associated with:1-3

• Aging
• Menopause
• Autoimmune diseases such as arthritis, lupus, and Sjögren’s Syndrome
• Medical conditions such as diabetes or blocked tear ducts

More specifically, lacrimal gland function and tear production in Chronic Dry Eye may be compromised in a number of ways:

• Decreased androgen levels found in aging patients, especially of post-menopausal women, appear to contribute to reduced lacrimal function
• Lymphocytic infiltration or age-related tissue damage may cause dysfunction of parts of the gland
• Tear production in Sjögren’s Syndrome patients (or patients with other autoimmune diseases) may be limited by autoantibodies directed against muscarinic M3 neurotransmitter receptors, causing a disconnect between neural signals and the acinar cells of the lacrimal gland
• The sensory or afferent portion of the neural loop may function poorly because of changes in tear composition or ocular surface tissue damage

Causative Factors vs. Exacerbating Factors

Chronic Dry Eye is among the least understood eye conditions that affect large numbers of the population. Many sufferers mistakenly attribute the cause of their symptoms to allergies, climatic conditions, or just “eyestrain.”

While environmental, occupational, and lifestyle factors, such as pollen, smoke, dry air, dust, the wearing of contact lenses for extended periods of time, and prolonged computer use – can all exacerbate Chronic Dry Eye, these factors are not the cause of the condition. It is important for patients to understand that they have a chronic medical condition, and to make the distinction between actual causes and exacerbating factors.

References:
1. Stern ME, Gao T, Siemasko KF, et al. The role of the lacrimal functional unit in the pathophysiology of dry eye. Ex Eye Res. 2004; 78:409-416.
2. Schaumberg DA, Sullivan DA, Buring JE, Dana MR. Prevalence of dry eye syndrome among US women. Am J Ophthalmol. 2003;136:2318-2326.
3. Sullivan DA, Wickham LA, Rocha EM, et al.  Influence of gender, sex steroid hormones, and the hypothalamic-pituitary axis on the structure and function of the lacrimal gland. In: Sullivan DA et al, eds.  Lacrimal Gland, Tear Film, and Dry Eye Syndromes 2. New York, NY: Plenum Press; 1998:11-42.