Some people do not produce enough tears to keep the front surface of the eye lubricated and comfortable. This condition is known as dry eye.
What is going on in the body?
Tears are secreted by nearby glands and have several purposes. They act to keep the front surface of the eye lubricated and moist. They also keep the surface smooth so that light enters the eye through a suitable surface for clear vision. The tears also contain antibacterial substances that protect against infection. Without enough tears, irritation or even damage to the front of the eye may occur.
What are the signs and symptoms of the condition?
One or, more commonly, both eyes can be affected. The eyes feel dry and people may have any of the following symptoms in their eyes:
Other symptoms are related to the cause of the dry eye.
- foreign body sensation
- stringy mucous in or around the eye
- increased irritation from wind, smoke, heat, or fumes
- difficulty wearing contact lenses
- stinging or burning
What are the causes and risks of the condition?
The risk of dry eye increases with age. This is because tear production normally decreases with age. Dry eye is also more common in women, especially after menopause.
Dry eye can be caused by:
Other causes are also possible. In some cases, the cause for dry eye cannot be found.
- autoimmune diseases. These are disorders in which a person's immune system attacks his or her body for no apparent reason. For example, in a condition called Sjogren syndrome, people get dry eyes, a dry mouth, and arthritis.
- medications such as diuretics or "water pills." Antihistamines, such as diphenhydramine, sleeping pills, medications for nerves, and pain relievers can also cause dry eye.
- neurologic disorders, such as Lou Gherig's disease, also called amyotrophic lateral sclerosis. In these conditions, the nerves that cause the glands to secrete tears are not working.
- damage or scarring of the front of the eye or the glands that make tears.
- eyelid problems, such as lids that cannot close properly.
- cancers, such as blood cancer, although this is rare.
- the environment. For example, when the humidity is very low, people may notice their eyes feel dry.
What can be done to prevent the condition?
Avoidance of dry environments can prevent some cases. Many cases cannot be prevented, only treated. Those who tend to get dry eye can use lubricating drops to avoid further episodes.
How is the condition diagnosed?
A medical eye doctor can usually diagnose dry eye by examining the eyes. There are painless methods of measuring tear production. For example, a small paper strip can be placed over the lower eyelid for about 5 minutes to measure the eye's ability to make tears. Another test involves placing a drop of stain in the eye to look for a particular pattern of staining on the surface of the eye. A full history and physical examination, blood tests, and other tests may be done.
What are the long-term effects of the condition?
Left untreated, dry eye can cause irritation and inflammation of the front of the eye. Worsening damage and scarring to the front of the eye, and even blindness may result. Serious long-term effects are unusual in Australia, but more common in underdeveloped countries.
What are the risks to others?
A dry eye is not contagious and poses no risk to others.
What are the treatments for the condition?
Treatment is directed at the cause, if one can be found. For example, medications may need to be stopped or changed. If the cause cannot be corrected, treatment is planned to relieve symptoms and prevent damage to the eye.
Artificial tears, in the form of drops, are the most common treatment. These can be bought without a prescription. These drops may need to be used often during the day because they only help moisten the eye for 1 to 2 hours at a time. The drops come in several different levels of thickness, or viscosity. Some people find that the thicker ones work better for them than the more watery forms. Artificial tears can be used as often as needed, once or twice a day, or even several times an hour. If a person needs to use artificial tears more than every 2 hours, preservative-free brands are advised.
People with extremely dry eyes may find that drops are not enough. They can use lubricating ointments in their eyes. These ointments are usually used at bedtime since they last longer through the night than a drop would and may impair vision while in the eye.
Another treatment is to conserve the tears. An eye doctor may insert plugs into the small openings on the eyelids that drain into the nose. Normally tears drain through these openings into the nose and then down the back of the throat. If this channel is plugged, the few tears one does make can stay on the surface of the eye longer, which may help lessen symptoms. The small openings can even be closed permanently with surgery if needed.
Using a humidifier to keep more moisture in the air can lessen evaporation of tears. Placing a pan of water on the radiator at night, especially during the winter, can also help keep room air moist. People with dry eye should avoid anything that may cause more dryness, such as an overly warm room, smoke, hair dryers, or wind.
The treatment of dry eye involves a long-term commitment. It should be understood that the condition is not likely to be cured, but it can be managed. It is rare for this condition to cause permanent visual loss. Dry eye is usually a matter of the comfort of the eye and possibly a temporary blurring of vision.
What are the side effects of the treatments?
Some artificial tears have preservatives that can cause side effects in people with dry eye. These include burning, itching, and allergic reactions. There are preservative-free artificial tears that those individuals can use.
If surgery is done, there is a very small risk of infection or reaction to any pain medication used.
What happens after treatment for the condition?
If treatment is successful, no further treatment is needed. In many cases, however, people need ongoing treatment for quite some time. Other treatment may be needed for the cause of the dry eye.
How is the condition monitored?
Affected people can generally monitor their symptoms at home. In severe cases, regular eye examinations may be needed to monitor for eye damage.
Reviewer: eknowhow Medical Review Panel
Editor: Dr John Hearne
Last Updated: 1/05/2005
Potential conflict of interest information for reviewers available on request