Commonly known as pinkeye, conjunctivitis is an inflammation of the conjunctiva, the clear membrane that covers the white part of the eye and lines the inner surface of the eyelids. It is a fairly common condition and usually causes no danger to the eye or your child's vision. The inflammation can have many causes, the most common of which are infectious, allergic, and irritant.

Infectious conjunctivitis is usually caused by either bacteria or viruses. Many different bacteria can cause conjunctivitis but the most common are Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus. The organisms that cause the sexually transmitted diseases gonorrhea and chlamydia can also infect the eyes and cause conjunctivitis. This type of eye infection can occur in sexually active people and in newborns who acquire the infection at birth from their mothers. Viral conjunctivitis is common with several viral infections - most often with infections caused by adenoviruses or enteroviruses - and can occur during a common cold or the flu. A less common but more serious viral conjunctivitis is herpes simplex infection. Parasites and fungal infections are rare causes of conjunctivitis.

Allergic conjunctivitis occurs more frequently among children with allergic conditions such as hay fever. It is often seen only at certain times of the year, especially when caused by allergens such as grass or ragweed pollen. Other allergy-causing substances like animal dander or dust mites can cause year-round symptoms of conjunctivitis. Although other forms of conjunctivitis often start in one eye, allergic conjunctivitis typically affects both eyes at the same time.

Irritant conjunctivitis can be caused by chemicals such as those in chlorine and soaps or air pollutants such as smoke and fumes.

When conjunctivitis occurs in babies younger than 4 weeks old, it is called neonatal conjunctivitis or ophthalmia neonatorum. This can be caused by a blocked tear duct, which can be treated by gentle massage between the eye and nasal area. Irritation from the antibiotic eyedrops regularly given to babies immediately after birth can cause a mild chemical conjunctivitis, which clears up on its own within a couple of days.

Newborns are also susceptible to infectious conjunctivitis, which can be serious. The sexually transmitted bacteria Chlamydia trachomatis and Neisseria gonorrhoeae can pass from an infected mother's birth canal into her baby's eyes during delivery. These bacteria can cause symptoms of conjunctivitis in babies within the first 2 weeks of life, and both can lead to serious eye damage. Less commonly, the viruses that cause genital and oral herpes can similarly be passed to an infant at the time of delivery and may also damage the eyes.

What Are the Signs and Symptoms?

The different types of conjunctivitis can have different symptoms. In addition, symptoms may vary from child to child.

One of the most common symptoms is discomfort or pain in the eye, which may feel like having sand in the eye. Many children have redness of the eye and inner eyelid as well; this redness led people to call conjunctivitis by its other common name, pinkeye. The child may also have swollen eyelids and be sensitive to bright light. Itchiness and tearing are common with allergic conjunctivitis.

Discharge from the eyes may accompany the other symptoms. In bacterial conjunctivitis, the discharge will be somewhat thick and colored white, yellow, or green. Sometimes the discharge will cause the eyelids to stick together when the child awakens in the morning. In viral or allergic conjunctivitis, the discharge may be thinner and may be clear.

Ear infections can occur in some children who are diagnosed with bacterial conjunctivitis because similar bacteria can cause both infections. A red, sore throat and runny nose often accompany conjunctivitis caused by viruses.

Is It Contagious?

All types of infectious conjunctivitis are contagious and can spread from one eye to the other by touching the eyes. A child can first become infected from direct contact with someone who has the infection or something that person has touched, such as a used tissue. The infectious organisms can also spread through coughing and sneezing. In addition, certain viruses spread in the summertime when children swim in contaminated water or share contaminated towels.

Allergic and irritant conjunctivitis are not contagious.

The incubation time for bacterial conjunctivitis is a few days. In viral cases, it can be up to a week.

Can It Be Prevented?

To prevent infectious conjunctivitis, teach your child to wash his or her hands often with warm water and soap. Children also should not share eyedrops, tissues, eye makeup, washcloths, towels, or pillowcases with other people.

If your child already has conjunctivitis, ask your child to wash his or her hands after touching the eyes. Your child also should not touch the infected eye and then touch the other eye without first washing his or her hands. Be sure to wash your own hands thoroughly after touching your child's eyes, and throw away items like gauze or cotton balls after they have been used. Wash towels and other linens that your child has used in hot water separately from the rest of the family's laundry to avoid contamination.

If you know your child is prone to allergic conjunctivitis, keep windows and doors closed on days when the pollen is heavy, and dust and vacuum frequently to limit allergy triggers in the home. Irritant conjunctivitis can only be prevented by avoiding the irritating causes