Dry Eye

Eyesight depends on a complex series of interactions between the different parts of the eye. (Read about "The Eye") One job of the eye is the continuous production and drainage of tears to keep vision clear and protect against infection. (Read about "Microorganisms") Tears keep the eye moist, wash away irritants and help wounds heal. When not enough or poor quality tears are produced, the resulting condition is called dry eye. Dry eye causes eyes to become irritated and uncomfortable. Some people experience blurred, changed or decreased vision. In very rare cases, dry eye could even cause blindness without proper treatment.

Symptoms

The usual symptoms of dry eye, according to the American Optometric Association (AOA), include:

• stinging or burning eyes
• scratchiness
• pain and redness
• stringy mucus in or around the eyes
• excess tearing
• difficulty wearing contact lenses

In a healthy eye, blinking leaves a "tear film" over the surface of the eye to keep it smooth and clear. Without the tear film, good vision would not be possible. The tear film consists of three layers, an oily layer on the outside, a watery layer in the middle and an inner layer of mucus. The oily layer helps tears remain on the eye and keeps them from evaporating too quickly. The watery layer cleanses the eye and washes away irritants. This watery layer is what we usually call tears. The mucus layer allows the watery layer to spread evenly over the surface of the eye and keep it moist. In people with dry eye, either not enough tears are produced and/or the tear film is of such poor quality that tears can't remain in the eye long enough to keep it lubricated.

Causes and risk factors

Tear production normally decreases as we get older, but dry eye can affect both men and women of any age. However, it is more common in women, especially after menopause. (Read about "Menopause") Dry eye can also be associated with other problems, such as Bell's palsy and rheumatoid arthritis. (Read about "Bell's Palsy" "Rheumatoid Arthritis") Dry eye and arthritis together can be a sign of a disease called Sjögren's syndrome (Read about "Sjögren's Syndrome"), according to Prevent Blindness America (PBA).

Eye surgery can also lead to dry eye. The Food and Drug Administration (FDA) says dry eye can be a complication of refractive surgery. (Read about "Refractive Errors: Myopia, Hyperopia, Astigmatism and Presbyopia") According to FDA, dry eye not only causes discomfort, but can reduce visual quality due to intermittent blurring and other visual symptoms. FDA says that for some people, the condition may be permanent, and intensive drop therapy and use of plugs may be needed.

Many people find their eyes get tired and feel dry when sitting in front of a computer. Adjusting your monitor to reduce glare can help, as can blinking more often. (Read about "Computers and Health")

The American Academy of Ophthalmology (AAO) says a wide variety of medications can also cause dry eye, including:

• antihistamines
• nasal decongestants
• sleeping pills
• pain relievers
• antidepressants
• diuretics
• beta-blockers

It's a good idea to tell your doctor what medications you are taking, since some may make the symptoms of dry eye worse. (Read about "Drug Interaction Precautions")

Treatment

The National Eye Institute (NEI) says treatment for dry eye often consists of simple over-the-counter tear replacements called "artificial tears." These eye drops lubricate the eyes and replace much needed moisture. There are many brands available without a prescription, including preservative-free brands for sensitive eyes. Your doctor can help you choose which kind is best for you and instruct you on how often to use it.

There are also artificial tear ointments that can be used at bedtime to keep eyes from drying out overnight, according to PBA, but because these can involve frequent use over long periods of time, they may cause irritation or allergic reactions. (Read about "Allergies") Be sure to check with your doctor before using them.

Cyclosporine, an anti-inflammatory medication, is a prescription drug available to treat dry eye. It decreases corneal damage, increases basic tear production, and reduces symptoms of dry eye. It may take three to six months of twice-a-day dosages for the medication to work. In some cases of severe dry eye, short term use of corticosteroid eye drops that decrease inflammation is required. There is also a class of drugs called lymphocyte function-associated antigen 1 (LFA-1) antagonists, that can be used.

AAO says other steps you can take to help relieve dry eye include:

• using a humidifier to add moisture to your room
• wearing wrap-around glasses to keep dry wind out of your eyes
• not using a hair dryer
• avoiding smoke

AAO says more serious treatment, usually for severe dry eye, can include closing the tear drains with special plugs to conserve your own tears. Tears drain out through a small opening at the inner corner of the eyelids. Closing these drains may help conserve your own tears and help artificial tears last longer.