What Causes Conjunctivitis?

There are many bacterial and viral causes of conjunctivitis. Common bacterial causes include Staphylococcus aureus, Haemophilus influenza, Streptococcus pneumoniae, Neisseria gonorrhea and Chlamydia trachomatis. Common viral causes include adenoviruses and herpes virus. Conjunctivitis can also be caused by chemicals (seen mostly in the newborn period, after the use of medicine in the eye to prevent other problems) and allergies.

What Are the Symptoms of Conjunctivitis?

Conjunctivitis is usually divided into at least two categories, newborn conjunctivitis and childhood conjunctivitis, with different causes and treatments for each.

Newborn Conjunctivitis

The most common causes and treatment options of newborn conjunctivitis are:

• Chemical conjunctivitis — Chemical conjunctivitis is related to an irritation in the eye from the use of eye drops that are given to the newborn to help prevent a bacterial infection. Sometimes, the newborn reacts to the drops and may develop a chemical conjunctivitis. The eyes are usually mildly red and inflamed, starting a few hours after the drops have been placed in the eye, and lasts for only 24 to 36 hours. This type of conjunctivitis usually does not require treatment and rarely occurs with present medications.
• Gonococcal conjunctivitis — Gonococcal conjunctivitis is caused by bacteria called Neisseria gonorrhea. The newborn obtains this type of conjunctivitis by the passage through the birth canal from an infected mother. This type of conjunctivitis may be prevented with the use of eye drops in newborns at birth. The newborn eyes usually are very red, with thick drainage and swelling of the eyelids. This type usually starts about 2 to 4 days after birth. Treatment for gonococcal conjunctivitis usually will include antibiotics through an intravenous (IV) catheter.
• Inclusion conjunctivitis — Inclusion conjunctivitis is caused by an infection with Chlamydia trachomatis. The symptoms include moderate drainage from the eyes, redness of the eyes, swelling of the conjunctiva, and some swelling of the eyelids. This type of conjunctivitis usually starts 5 to 12 days after birth. Treatment usually will include oral antibiotics.
• Other bacterial causes — After the first week of life, other bacteria may be the cause of conjunctivitis in the newborn. The eyes may be red and swollen with some drainage. Treatment depends on the type of bacteria that has caused the infection. Treatment usually will include antibiotic drops or ointments to the eye, warm compresses to the eye, and proper hygiene when touching the infected eyes.

Childhood Conjunctivitis

Childhood conjunctivitis is a swelling of the conjunctiva and may also include an infection. It is a very common problem in children. Also, large outbreaks of conjunctivitis are often seen in daycare settings or schools. The following are the most common causes of childhood conjunctivitis:

Symptoms may include:

• Itchy, irritated eyes
• Clear, thin drainage (usually seen with viral or allergic causes)
• Sneezing and runny nose (usually see with allergic causes)
• Stringy discharge from the eyes (usually seen with allergic causes)
• Thick, green drainage (usually seen with bacterial causes)
• Ear infection (usually seen with bacterial causes)
• Lesion on eyelids with a crusty appearance (usually seen with herpes infection)
• Eyelids that are matted together in the morning
• Swelling of the eyelids
• Redness of the conjunctiva
• Discomfort when the child looks at a light
• Burning in the eyes

The symptoms of conjunctivitis may resemble other medical conditions or problems. Always consult your child's physician for a diagnosis.

What Is the Treatment for Conjunctivitis?

Conjunctivitis is usually diagnosed based on a complete medical history and physical examination of your child's eye. Cultures of the eye drainage are usually not required but may be done to help confirm the cause of the infection.

Specific treatment depends on the underlying cause of conjunctivitis:

• Bacterial causes — Your child's physician may order antibiotic drops to put in the eyes.
• Viral causes — Viral conjunctivitis usually does not require treatment. Your child's physician may order antibiotic drops for the eyes to help decrease the chance of a secondary infection.
• Allergic causes — Treatment for conjunctivitis caused by allergies usually will involve treating the allergies. Your child's physician may order oral medications or eye drops to help with the allergies.
• Herpes — If your child has an infection of the eye caused by a herpes infection, your child's physician may refer you to an eye care specialist. Your child may be given both oral medications and eye drops.

Infection can be spread from one eye to the other, or to other people, by touching the affected eye or drainage from the eye. Proper hand washing is very important. Drainage from the eye is contagious for 24 to 48 hours after beginning treatment.

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