A condition known as "dry eye",  is caused when the eye does not produce enough tears to keep it moist and comfortable. It is the most common of all eye disorders affecting over 20% of Americans.

The eye uses two different methods to produce tears. It can make tears at a slow, steady rate to maintain normal eye lubrication. It can also produce large quantities of tears in response to eye irritation or emotion. When a foreign body or dryness irritates the eye, or when a person cries, excessive tearing occurs.

Symptoms

• Stinging or burning eyes
• Red eyes
• Scratchiness, sandy or gritty feeling
• Foreign body sensation
• Sensitivity to light
• Stringy mucus in or around the eyes
• Excessive eye irritation from smoke or wind
• Excess tearing
• Discomfort when wearing contact lenses
• Seasonal allergies

Excess tearing from "dry eye" may sound strange, but it can be understood as the eye's response to discomfort. If the tears responsible for maintaining lubrication do not keep the eye wet enough, the eye becomes irritated. Eye irritation prompts the gland that makes tears (called the lacrimal gland) to release a large volume of tears, overwhelming the tear drainage system. These excess tears then overflow from your eye.

Causes of Dry Eye Syndrome

Tear production normally decreases as we age. Although dry eye can occur in both men and women at any age, women are most often affected. This is especially true after menopause.

Dry eye can also be associated with other problems. For example, people with dry eye, dry mouth, and arthritis are said to have Sjogren's syndrome.

A wide variety of common medications-both prescription and over-the-counter-can cause dry eye by reducing tear secretion. Be sure to tell your eye doctor the names of all the medications you are taking, especially if you are using:

• Diuretics
• Beta-Blockers
• Antihistamines
• Sleeping Pills
• Medications for "nerves"
• Pain relievers

Since these medications are often necessary, the dry eye condition may have to be tolerated or treated with eye drops called artificial tears.

People with dry eye are often more prone to the toxic side effects of eye medications, including artificial tears. For example, the preservatives in certain eye drops and artificial tear preparations can irritate the eye. These people may need special preservative-free artificial tears.

Diagnosing and Treating Dry Eye

Your eye doctor is usually able to diagnose dry eye by examining the eyes. Sometimes test that measure tear production are necessary. One test, called the Schirmer tear test, involves placing filter-paper strips under the lower eyelids to measure the rate of tear production under various conditions. Another test uses a diagnostic drop (called fluroscein or rose bengal) to look for certain patterns of dryness on the surface of the eye.

Adding artificial tears similar to your own natural tears to your eyes is one way to treat dry eyes. They lubricate the eyes and help maintain moisture. Artificial tears are available without a prescription. There are many brands on the markets, so you may want to try several to find the one you like best.

Preservative-free eye drops are available for people who are sensitive to the preservatives in artificial tears. If you need to use artificial tears more than every two hours, preservative free brands may be better for you.

You can use the artificial tears as often as necessary-once or twice a day or as often as several times an hour.

Conserving your eyes' own tear is another approach to keeping the eyes moist. Tears drain out of the eye through a small channel into the nose (which is why your nose runs when you cry). Your ophthalmologist may close these channels either temporarily or permanently. The closure conserves your own tears and makes artificial tears last longer.

Other Methods

Tears evaporate like any other liquid. You can take steps to prevent evaporation. In winter when indoor heating is in use, a humidifier or a pan of water on the radiator adds moisture to dry air. Wrap-around glasses may reduce the drying effect of the wind, but you should not that they are illegal to wear while driving in some states.

A person with dry eye should avoid anything that may cause dryness, such as an overly warm room, hair dryers, or wind. Smoking is especially bothersome.

Some people with dry eye complain of "scratchy eyes" when they wake up. This symptom can be treated by using an artificial tear ointment or thick eye drops at bedtime. Use the smallest amount of ointment necessary for comfort, since the ointment can cause your vision to blur.

Dry eye due to lack of Vitamin A in the diet is rare in the United States but is more common in poorer countries, especially among children. Ointments containing vitamin A can help dry eye if it is caused by unusual conditions such as Stevens-Johnson syndrome or pemphigoid. Vitamin A supplements do not seem to help people with ordinary dry eye.

Simple lifestyle changes can help improve irritation from dry eye as well. Drinking eight to ten glasses of water a day helps flush impurities that can aggravate your eyes. Making a conscious effort to blink frequently also helps. Avoid rubbing your eyes, as this will only aggravate dry eye symptoms.