Conjunctivitis is an infection or inflammation of the conjunctivae, the thin clear membranes that cover the white part of the eyeballs and line the inside of the eyelids.
Conjunctivitis is a medical condition in which the conjunctivae appear pink or red, and the eyes water and feel irritated. In some cases the eyes may feel scratchy or itchy as well. Conjunctivitis can be caused by a bacterial, chlamydial, or viral infection; by seasonal allergies; by a foreign object in the eye; by a chemical irritant; or by such other medical conditions as dry eye. There may be mild sensitivity to light, a condition known as photophobia.
There are no exact statistics on the number of cases of conjunctivitis in the United States each year because the condition has so many possible causes, but it is the single most common reason for a person's consulting an eye doctor. Between 1 and 2 percent of babies born in the United States each year have ophthalmia neonatorum, a bacterial conjunctivitis caused by a sexually transmitted disease in the mother.
Causes and Symptoms
Conjunctivitis may have a number of different causes. Some are not contagious, while others can be transmitted from person to person. The symptoms also vary somewhat depending on the cause:
- Allergic conjunctivitis. Allergic conjunctivitis is caused by pollen, dust, and the other types of allergens that cause hay fever and other seasonal allergies in some people. Both eyes are usually affected. The eyes are usually very watery and itchy in this type of conjunctivitis, and the eyelids may swell up or look puffy.
- Viral conjunctivitis. This type of conjunctivitis is contagious and often gets started when viruses from an upper respiratory infection
like a cold are carried into the eye by hand-to-eye contact. The infection usually starts in one eye but often spreads to the other within a day or two. The discharge from the eye is usually watery. A person with viral conjunctivitis is contagious for one to two weeks after their symptoms first appear.
- Bacterial conjunctivitis. Like viral conjunctivitis, this type is also contagious and can be spread by sexual contact with someone infected with gonorrhea or chlamydia as well as by hand-to-eye transmission. Pregnant women infected with gonorrhea or chlamydia can give their babies a particularly dangerous type of bacterial conjunctivitis during childbirth known as ophthalmia neonatorum, which can cause blindness if untreated. Bacterial conjunctivitis is often accompanied by a gritty or sandy feeling in the eyes and a yellowish or grayish pus-filled discharge that causes the eyelids to stick together during sleep. Bacterial conjunctivitis usually appears within three days after the person is infected with the bacteria. Like viral conjunctivitis, it often begins in one eye but can spread to the other.
- Chemical splash (toxic conjunctivitis). This type of conjunctivitis is noninfectious. It is caused by getting an irritating chemical in the eye (such as shampoo or chlorine from swimming in pool water) and usually affects only the lower part of the conjunctiva inside the lower eyelid. Redness of the affected eye is sometimes caused by flushing the eye to wash out the chemical.
- Foreign body in the eye. Like toxic conjunctivitis, this type of conjunctivitis is not infectious. It usually affects only one eye and may be accompanied by a mucus-like discharge.
- Chronic or recurrent conjunctivitis. Some people develop recurrent episodes of conjunctivitis from wearing contact lenses or overusing certain types of eye drops. This type of conjunctivitis is not contagious.
- Conjunctivitis associated with dry eyes or other eye disorders. Some eye disorders are associated with a gradual loss of normal tear secretions in the eye, which can lead to conjunctivitis.
In many cases conjunctivitis will clear up by itself in three to four days without the need to see a doctor. If the condition does not clear by itself, or if the discharge from the eye contains pus rather than being clear and watery, the person should see their doctor.
The doctor may take a sexual history or ask about recent exposure to colds and other viral illnesses or the patient's use of eye cosmetics or contact lenses to narrow the diagnostic possibilities. The doctor may also take a sample of the discharge from the affected eye or eyes for laboratory analysis in order to determine whether a bacterium or a virus is the cause.
Tips to Prevent Conjunctivitis
To lower the risk of getting conjunctivitis or spreading it to others, eye doctors recommend the following practices:
- Change pillowcases frequently and do not share bed pillows with others.
- Do not share eye cosmetics, cotton balls, gauze pads, or facial tissues.
- Replace mascara, eye liner, and eye shadow regularly even if the cosmetics have not been completely used up.
- Do not share towels, handkerchiefs, or washcloths.
- People who wear contact lenses should handle and clean them properly.
- Keep hands away from the eyes as much as possible.
- Wash the hands regularly.
Severe pain, intense photophobia, and blurred vision are not usually present in uncomplicated conjunctivitis. A patient with these symptoms should be examined further for more serious eye disorders, including glaucoma or inflammation of the interior of the eye. If the patient's eye has been irritated by a chemical, the doctor may examine the eye with a slit lamp to see whether the interior of the eye has also been affected.
Treatment of conjunctivitis depends on the cause of the infection or irritation. Allergic or seasonal conjunctivitis is usually relieved by applying cool compresses to the eyes or by using artificial tears. This type of conjunctivitis can also be treated with antihistamines, steroids, or other anti-inflammatory medications.
Bacterial infections are treated with antibiotic eye ointments or drops. There are no specific treatments for viral conjunctivitis; the illness must simply be allowed to go away on its own. Warm compresses or artificial tears may help to ease the patient's discomfort. Viral conjunctivitis may get worse for the first three to five days of the infection and then gradually get better; it can take as long as three to four weeks for viral conjunctivitis to clear up completely.
Foreign bodies or chemicals in the eye are usually washed out with saline solution. A chemical splash involving a caustic substance like lye is a medical emergency and should be treated by an emergency room physician or eye specialist as soon as possible.
The prognosis of conjunctivitis depends on its cause. Most people recover with no problems provided they follow the doctor's instructions for their particular type of conjunctivitis and practice good eye hygiene in general. The only type of conjunctivitis in adults that may cause permanent loss of vision is a chemical splash injury involving caustic chemicals such as lye or potash.
Ophthalmia neonatorum, however, can lead to blindness if it is not treated promptly. The usual treatments for bacterial infections of the eyes in newborns are silver nitrate eye drops or antibiotic medications.
While it is not always possible to prevent being exposed to people with upper respiratory infections in one's school or workplace, one can lower one's risk of conjunctivitis by keeping the hands clean, being careful when touching the eyes, following instructions for the proper use and cleansing of contact lenses, and avoiding sharing washcloths and other personal items with others. Additional guidelines for preventing conjunctivitis are listed in the sidebar.
Conjunctivitis has so many different causes that it is likely to continue to be a commonplace health concern for the foreseeable future.
SEE ALSO Chlamydia; Glaucoma; Gonorrhea; Hay fever
WORDS TO KNOW
Allergen : Any substance that causes an allergic reaction in a person or animal.
Chlamydia : A sexually transmitted disease caused by a bacterium that is a common cause of eye infections.
Conjunctiva (plural, conjunctivae) : The clear membrane that covers the white part of the eyeball and lines the eyelids.
Ophthalmia neonatorum : The medical name for bacterial conjunctivitis in newborn babies caused by a sexually transmitted infection in the mother.
Photophobia : A feeling of discomfort or pain in the eyes during exposure to light.
Slit lamp : An instrument that focuses light into a thin slit. It is used by eye doctors to examine eyes for a wide variety of disorders.
For more information
Bakri, Sophie J., ed. Mayo Clinic Guide to Better Vision. Rochester, MN: Mayo Clinic, 2007.
Zernike, Kate. “Pinkeye Cases Baffle 2 Ivy League Colleges.” New York Times, March 17, 2002. Available online at http://query.nytimes.com/gst/fullpage.html?res=9403E2D61638F934A25750C0A9649C8B63 (accessed May 6, 2008). This is a news item about an epidemic of bacterial conjunctivitis at the college level.
Mayo Clinic. Pink Eye (Conjunctivitis). Available online at http://www.mayoclinic.com/health/pink-eye/DS00258 (updated May 25, 2006; accessed May 6, 2008).
National Eye Institute (NEI). Facts about the Cornea and Corneal Disease. Available online at http://www.nei.nih.gov/health/cornealdisease/#b (updated December 2007; accessed May 6, 2008).
TeensHealth. Pinkeye (Conjunctivitis). Available online at http://www.kidshealth.org/teen/infections/common/conjunctivitis.html (updated November 2006; accessed May 6, 2008).