What is conjunctivitis?

Quick Answer
An acute inflammatory disease of the eye caused by infection or irritation.
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Causes and Symptoms

Conjunctivitis, or pinkeye, is one of the most common eye disorders. The conjunctiva is a thin translucent membrane that overlies the white part of the eye and the inner surface of the eyelids. It protects the eye from foreign objects and infection.

The conjunctiva may become inflamed through infection with a virus or bacterium, allergic reactions, and exposure to certain chemicals. Inflammation of the conjunctiva brings increased blood flow to the eye, producing a red or bloodshot appearance. Conjunctivitis causes a feeling of irritation, burning, or mild pain. A discharge often occurs, which may form a crust on the eyelids when it dries. Conjunctivitis does not cause visual loss, fever, or severe pain. It is typically mild and short-lived, lasting from a few days to a few weeks.

Most conjunctivitis is caused by infection and is highly contagious, spreading quickly from one eye to the other and from person to person by touch. Viral conjunctivitis will resolve without treatment, although symptoms may persist as long as a few weeks. Upper-respiratory symptoms may occur simultaneously because similar viruses cause the common cold. These viruses may live on surfaces for several hours and can be transmitted in poorly chlorinated swimming pools. Bacterial conjunctivitis causes a thicker discharge and more severe crusting. It is caused by various bacteria, and all respond well to topical antibiotics.

Allergic conjunctivitis may be stimulated by a reaction to dust, mold, animal dander, or pollen. It causes burning or itching in both eyes and occurs in a seasonal pattern. Chemicals, wind, dust, smoke, and chronic dry eyes can also cause direct irritation of the conjunctiva.

Treatment and Therapy

For viral conjunctivitis, no therapy is required, but the patient may be contagious for as long as two weeks. Common bacterial conjunctivitis resolves quickly with antibiotic eyedrops or ointment. A person remains contagious with bacterial conjunctivitis until after twenty-four hours of antibiotic treatment. The spread of infection can be prevented by washing one’s hands frequently, using separate towels, and isolating an infected child from interaction with other children for the first twenty-four hours of treatment. For allergic conjunctivitis, avoiding the offending allergen and using topical antihistamines or artificial tears are effective treatments.

Perspective and Prospects

Conjunctivitis is generally benign and rarely causes permanent injury. However, in many developing countries, conjunctivitis is a leading cause of blindness. In areas of extreme poverty, repeated infections with trachoma, a bacterial infection spread by flies, can lead to permanent scarring of the eyes. Newborns may also contract severe bacterial conjunctivitis from the mother’s cervix during birth. For this reason, most developed nations require that all newborns receive antibiotic eyedrops at birth.


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