In pink eye (conjunctivitis), the membrane that lines the eyelids and covers the eye becomes inflamed and swollen. The infected area (infected conjunctiva) of the eye is shown in green.
Pink eye, also known as conjunctivitis (kon-jung-tih-VY-tis) is an inflammation of the conjunctiva (kon-jung-TIE-vuh), the thin membrane that lines the inside of the eyelids and covers the surface of the eyeball. Conjunctivitis can be caused by viruses, bacteria, allergies, or chemical irritation.
Pink eye is an inflammation of the thin membrane that lines the inside of the eyelids and covers the white surface of the eye. The inflammation can produce redness, burning, or itching of the eyes and sometimes a discharge. Bacterial or viral infections most often cause pink eye. Many different bacteria can be the culprit, most commonly Streptococcus pneumoniae (strep-tuh-KAH-kus nu-MO-nye), Haemophilus influenzae (he-MOH-fih-lus in-floo-EN-zuh), and Staphylococcus aureus (stah-fih-lo-KAH-kus AREree-us). Infections with adenovirus * and influenza viruses are common causes of pink eye. About 80 percent of all cases of pink eye result from viral or bacterial infection.
On rare occasions parasite * and fungal infections can cause pink eye. The condition also can stem from various allergies, irritants, chemicals, and pollutants. Reactions to smoke, dust, makeup, contact lenses, and pollen all can produce symptoms in some people, as can contaminated contact lens solution in contact lens wearers.
The sexually transmitted diseases chlamydia * and gonorrhea * , which can be passed from infected mothers to their babies during birth, are the most common causes of pink eye in newborns. These two diseases can lead to pink eye in adults as well. Pink eye usually does not cause problems with vision.
The first symptoms typically appear within a few days or up to a week after infection. A person may feel discomfort, a gritty sensation under the eyelids, or a feeling that there is something in the eye. Redness develops in the eye, and the eyelids may swell. Bacterial infections usually produce a thick yellowish or greenish discharge. When the person wakes up in the morning, the eyelids might stick together as the result of dried discharge. In viral conjunctivitis, the discharge is often thin, watery, and clear. Viral infections are more likely to affect both eyes and can be accompanied by other symptoms of viral infection, such as cold or flu symptoms.
Eye discharge and inflammation (redness) of the conjunctiva are the hallmarks of pink eye. The doctor also will ask whether the person has had recent contact with someone with pink eye and will examine the eyes, making sure the person's vision is normal. Sometimes the doctor will swab the inside of the eyelids to obtain fluid for laboratory testing to determine the type of infection. This procedure is more likely to be done in newborn babies or someone at risk of a sexually transmitted disease, such as chlamydial infection or gonorrhea.
Treatment depends on the cause. If bacterial conjunctivitis has been diagnosed, antibiotic eyedrops usually are prescribed for about a week. An antibiotic ointment is used for babies. Viral conjunctivitis disappears by itself in about two weeks and does not typically require treatment. (One exception is conjunctivitis caused by herpesvirus * infection, which is treated with antiviral eyedrops.) Over-the-counter pain relievers, such as acetaminophen *
Complications of pink eye are rare. In newborns, untreated gonorrheal infection of the conjunctiva can cause a spreading infection of the eye that can lead to blindness. A few viruses cause pink eye that affects deeper parts of the eye, resulting in keratitis (kare-uh-TY-tis), an inflammation of the cornea * that causes changes in vision and sometimes permanent scarring of the cornea. Trachoma (truh-KOmah), a type of chlamydial conjunctivitis seen in developing countries, also can lead to blindness.
Good hygiene is the best way to help prevent infectious pink eye. People should wash their hands frequently, especially after touching the face of someone who has the infection. Eye cosmetics should be replaced regularly, and contact lenses should be handled and cleaned properly. It is a good idea for people with infectious conjunctivitis to wash their hands often to avoid spreading the infection. It is also wise not to share makeup; disposable items, such as paper towels and cotton balls; or towels. Washing towels and clothing in hot water can disinfect them.
See also Allergies • Bacterial Infections • Chlamydial Infections • Common Cold • Eye Disorders: Overview • Fungal Infections • Gonorrhea • Herpes Simplex Virus Infections • Infection • Influenza • Parasitic Diseases: Overview • Sexually Transmitted Infections (STIs): Overview • Staphylococcal Infections • Streptococcal Infections • Viral Infections
Field, Dorothy, Julie Tillotson, and Emma Whittingham. Eye Emergencies: The Practitioner's Guide, 2nd ed. Cumbria, UK: M&K Publishing, 2015.
Centers for Disease Control and Prevention. “Conjunctivitis (Pink Eye).” http://www.cdc.gov/conjunctivitis/ (accessed April 1, 2016).
Merck Manual: Consumer Version. “Infectious Conjunctivitis.” http://www.merckmanuals.com/home/eye-disorders/conjunctival-and-scleral-disorders/infectious-conjunctivitis (accessed April 1, 2016).
American Optometric Association. 243 N. Lindbergh Blvd., Flr. 1, St. Louis, MO 63141. Toll-free: 800-365-2219. Website: http://www.aoa.org (accessed April 1, 2016).
Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30329-4027. Toll-free: 800-232-4636. Website: http://www.cdc.gov (accessed April 1, 2016).
National Eye Institute. Information Office, 31 Center Drive, MSC 2510, Bethesda, MD 20892. Telephone: 301-496-5248. Website: https://nei.nih.gov (accessed April 1, 2016).
U.S. National Library of Medicine. 8600 Rockville Pike, Bethesda, MD 20894. Toll-free: 888-346-3656. Website: http://www.nlm.nih.gov (accessed April 1, 2016).
* adenovirus (ah-deh-no-VY-rus) is a type of virus that can produce a variety of symptoms, including upper respiratory disease, when it infects humans.
* parasite (PAIR-uh-site) is an organism such as a protozoan (one-celled animals), worm, or insect that must live on or inside a human or other organism to survive. An animal or plant harboring a parasite is called its host. A parasite lives at the expense of the host and may cause illness.
* chlamydia (kla-MIH-dee-uh) are microorganisms that can infect the urinary tract, genitals, eye, and respiratory tract, including the lungs.
* gonorrhea (gah-nuh-REE-uh) is a sexually transmitted disease (STD) spread through all forms of sexual intercourse. The bacteria can also be passed from an infected mother to her baby during childbirth. Gonorrhea can affect the genitals, urethra, rectum, eyes, throat, joints, and other tissues of the body.
* herpesvirus (her-peez-VY-rus) is a member of a family of viruses that can store themselves permanently in the body. The family includes zoster virus, Epstein-Barr virus, and herpes simplex virus.
* acetaminophen (uh-see-tehMIH-noh-fen) is a medication commonly used to reduce fever and relieve pain.
* cornea (KOR-nee-uh) is the transparent circular layer of cells over the central colored part of the eyeball (the iris) through which light enters the eye.