Dry Eye Effects at the Tissue Level

Dry eye, when tears are not formed properly, can be caused by many factors--including allergies, drug reactions, complications from certain diseases and menopause. The production of tears is essential to keeping the eyes healthy--especially for the cornea, which relies on tears for its nourishment.

Tear Physiology

• Tears are filmy liquids comprised of three layers. Closest to the cornea of the eye is the mucin layer of a tear which serves to make them viscous enough to spread out and cover the whole surface of the eye. Proceeding outward, the middle layer is the aqueous layer of a tear. This contains the substances to "nourish" and keep both the cornea and the conjunctiva healthy. The outer layer of a tear, called the lipid layer, is more oily. This layer prevents the tear from evaporating so that the eye itself has the most protection possible.

Function

• Tears keep the eyes healthy in four ways. First, they provide lubrication and nutrients to the eye's cornea and conjunctiva. Second, tears help the eye heal after it is injured. Third, like the windshield wipers on a car, tears keep the transparent cornea of each eye clean. Finally, tears serve to protect the eyes from infections. Of course, tears are released when someone cries after experiencing a strong emotional reaction.

Symptoms of Dry Eye

• People who have dry eye feel as though there are little pieces of sand or hard plastic bits that scratch and scrape between the eyelid and the surface of the eye. The eyes may sting or burn. There may be a goopy discharge, pain and even redness. Sometimes people who have dry eye cannot keep from releasing a lot of tears. They look as though they are crying. This experience may be followed by a sensation that the eyes have become very dry indeed. People who have dry eye may even experience distorted, blurred or diminishing vision.

Effects

• The effects of dry eye at the tissue level include a decreased ability to ward off ocular infections because the surface of the eye is not protected or sufficiently nourished. If the eye becomes scratched or otherwise injured because there were insufficient tears to protect the eye, the lack of sufficient tears may reduce the eye's ability to heal. Since the cornea is under-protected when a person has dry eye, the risk of injury is increased. Scratches, blisters, and corneal injuries can result in a loss of vision, increased potential for infection and general ocular discomfort.

Causes

• Women who are post-menopausal frequently experience dry eye. The condition is also caused by reactions to some medications including those used to treat congestion, allergies, sleeplessness and depression. It can also be caused by exposure to environmental pollutants, fumes and dust. Dry eye can also be a symptom of Rheumatoid Arthritis and Sjogren's syndrome.

Treatment

• If you think you may be suffering from dry eye, see your optometrist. Your eye doctor can prescribe one of several treatments depending on the severity and probable cause. The most common treatment for dry eye is to use drops that function in your eyes as "artificial tears."