What is dry eye?
Normally, the eye constantly bathes itself in tears. By producing tears at a slow and steady rate, the eye stays moist and comfortable.
Sometimes people do not produce enough tears or the appropriate quality of tears to keep their eyes healthy and comfortable. This condition is known as dry eye.
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.
What are the symptoms of dry eye?
The usual symptoms include:
- Stinging or burning eyes
- Stringy mucus in or around the eyes
- Excessive eye irritation from smoke or wind
- Excess tearing
- Discomfort when wearing contact lenses
Excess tearing from “dry eye” may sound illogical, 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.
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 withother problems. For example, people with dry eyes, dry mouth, and arthritis are said to have Sjögren’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:
- 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 eyedrops 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 eyedrops and artificial tear preparations can irritate the eye. These people may need special preservative-free artificial tears.
How is dry eye diagnosed?
An ophthalmologist is usually able to diagnose dry eye by examining the eyes. Sometimes tests 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 fluoresceinor rose bengal) to look for certain patterns of dryness on the surface of the eye.