Some people do not produce enough tears to keep the eye comfortable. This is known as dry eye. Tears are produced by two different methods. One method produces tears at a slow, steady rate and is responsible for normal eye lubrication. The other method produces large quantities of tears in response to eye irritation or emotions. Tears that lubricate are constantly produced by a healthy eye. Excessive tears occur when the eye is irritated by a foreign body or when a person cries.
What are the symptoms of dry eye?
The usual symptoms include:
Stinging or burning eyes
Stringy mucus in or around the eyes
Eye irritation from smoke and wind
Difficulty wearing contact lenses
Excess tearing from dry eye sounds like an oxymoron, but if the tears responsible for maintenance lubrication do not keep the eye wet enough the eye becomes irritated. The lacrimal gland then produces a large volume of tears which overwhelms the tear drainage system from your eye.
What causes dry eye?
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 arthritis and accompanied by a dry mouth. People with dry eyes, 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 ophthalmologist the names of all the medications you are taking, especially if you are using:
Medications for "nerves"
Since these medications are often necessary, the dry eye condition may have to be tolerated or treated with "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. Special preservative-free artificial tears may be required.
How is dry eye diagnosed?
We are usually able to diagnose dry eye by examining the eyes. Sometimes tests that measure tear production may be necessary. One test, called a Schrimer tear test, involves placing filter paper strips under the lower eyelids to measure the rate of tear production under various conditions. We can also test dry eye using a diagnostic drop to look for certain staining patterns.
How is dry eye treated?
Eye drops called artificial tears are similar to your own tears; they lubricate the eyes and help maintain moisture. Artificial tears are available without a prescription. There are many brands on the market, so you may want to try several to find the one you like best.
Preservative-free eye drops are available if you 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 tears as often as necessary - once or twice a day to several times an hour.
Conserving your eyes' own tears 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.
Tears evaporate like any other liquid. You can take steps to prevent evaporation. In winter when indoor heat is on, a humidifier adds moisture to dry air. Wrap around glasses reduce the drying effect of the wind.
Anything that may cause dryness, such as an overly warm room, hair dryers or wind, should be avoided by a person with dry eye. Smoking is especially bothersome.
Some people with dry eye complain of "scratchy eyes" when they wake up. This symptom can be treated by using artificial tear ointment at bedtime. Use the smallest amount of ointment necessary for comfort, since the ointment can cause your vision to blur temporarily.