Dry eye syndrome is one of the most common conditions treated by eye physicians. Over ten million Americans suffer from dry eyes. Dry eye syndrome is usually caused by a problem with the quality of the tear film that lubricates the ocular surface.
Tears are comprised of three layers. The mucus layer coats the cornea, the eye’s clear outer window, forming a foundation for the tear film to adhere. The middle aqueous layer provides moisture and supplies oxygen and other important nutrients to the cornea. This layer is 98 percent water. The outer lipid layer is an oily film that seals the tear film on the eye and helps to prevent evaporation.
Tears are formed in several glands around the eye. The water layer is produced in the lacrimal gland, located under the upper eyelid. Several smaller glands in the lids make the oil and mucus layers. With each blink, the eyelids spread the tears over the eye. Excess tears flow into two tiny drainage ducts in the corner of the eye by the nose. These ducts lead to tiny canals that connect to the nasal passage. The connection between the tear ducts and the nasal passage is the reason that crying causes a runny nose.
In addition to lubricating the eye, tears are also produced as a reflex response to outside stimuli such as injury or emotion. However, reflex tears do little to soothe a dry eye, which is why someone with watery eyes may still experience irritation.
Dry eye syndrome has many causes. One of the most common reasons for dryness is simply the normal aging process. As we grow older, our bodies produce less oil—60% less at age 65 than at age 18. This is more pronounced in women, who tend to have drier skin than men. The oil deficiency also affects the tear film. Without as much oil to seal the watery layer, the tear film evaporates much faster, leaving dry areas on the cornea.
Many other factors, such as hot, dry or windy climates, high altitudes, air-conditioning and cigarette smoke also cause dry eyes. Many people also find their eyes become irritated when reading or working on a computer. Stopping periodically to rest and blink keeps the eyes more comfortable.
Contact lens wearers may also suffer from dry eyes. Contact lenses tend to absorb the tear film, causing proteins to form on the surface of the lens. Certain medications, thyroid conditions, autoimmune diseases such as rheumatoid arthritis and lupus, vitamin A deficiency, Parkinson’s disease, and Sjogren’s can also cause dry eyes. Women frequently experience problems with dry eyes as they enter menopause because of hormonal changes.
Dry eye syndrome is an ongoing condition that may not be cured. The accompanying dryness, scratchiness, and burning can be managed. Your doctor may prescribe artificial tears—lubricating eye drops to alleviate the dry, scratchy feeling.
Your doctor may also prescribe Restasis (cyclosporine in a castor oil base). This eye drop medication can increase tear production in some patients. Restasis is normally used twice a day. It often takes several weeks before symptoms improve.
Temporary or permanent silicone plugs called punctal plugs can be placed in the lacrimal (tear) ducts to keep tears in your eye from draining as quickly. It only takes a few minutes to insert these plugs in the office.
Doctors sometimes recommend special nutritional supplements for dry eyes. Studies have found that supplements containing certain essential fatty acids can decrease dry eye symptoms. You can also increase your intake of omega-3 fatty acids which are commonly found in cold water fish such as sardines, cod, herring, and salmon.