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Infectious conjunctivitis is inflammation of the conjunctiva usually caused by viruses or bacteria.

• Bacteria and viruses can infect the conjunctiva.
• Redness, irritation, tearing or discharge, and sensitivity to light are common.
• Good hygiene helps prevent the infection from spreading.
• Antibiotic eye drops are often given.

A variety of microorganisms may infect the conjunctiva. The most common organisms are viral, particularly those from the group known as adenoviruses. Bacterial infections are less frequent. Both viral and bacterial conjunctivitis are quite contagious, easily passing from one person to another, or from a person's infected eye to the uninfected eye. Fungal infections are rare and occur mainly in people who use corticosteroid eye drops for a long time or have eye injuries involving vegetable matter. Newborns are particularly susceptible to eye infections, which they acquire from organisms in the mother's birth canal (neonatal conjunctivitis—see Problems in Newborns: Some Infections of Newborns).

Inclusion conjunctivitis is a particularly long-lasting form of conjunctivitis caused by certain strains of the bacterium Chlamydia trachomatis. Inclusion conjunctivitis usually spreads by contact with genital secretions from a person who has a genital chlamydial infection. Trachoma (see Conjunctival and Scleral Disorders: Trachoma) is another type of conjunctivitis caused by Chlamydia trachomatis. Another type of conjunctivitis is caused by Neisseria gonorrhoeae (gonorrhea), a sexually transmitted disease that also may spread to the eye.

Severe infections may scar the conjunctiva, causing abnormalities in the tear film. Sometimes, severe conjunctival infections spread to the cornea (the transparent part of the eye).

Symptoms

When infected, the eye sometimes feels irritated, and bright light may cause discomfort. The conjunctiva becomes pink from dilated blood vessels, and a discharge appears in the eye. Often the discharge causes the person's eyes to stick shut, particularly overnight. This discharge may also cause the vision to blur. Vision improves when the discharge is blinked away. If the cornea is infected, vision also blurs but does not improve with blinking. Very rarely, severe infections that have scarred the conjunctiva lead to long-term vision difficulties.

Conjunctivitis

Viral conjunctivitis differs from bacterial conjunctivitis in the following ways:

• Eye discharge tends to be watery in viral conjunctivitis and thicker white or yellow in bacterial conjunctivitis.
• An upper respiratory infection increases the likelihood of a viral cause.
• A lymph node in front of the ear may be swollen and painful in viral conjunctivitis but is usually not in bacterial conjunctivitis.

These factors, however, cannot always accurately differentiate viral conjunctivitis from bacterial conjunctivitis.

People with inclusion conjunctivitis or with conjunctivitis caused by gonorrhea often have symptoms of a genital infection, such as penile or vaginal discharge and burning during urination.

Diagnosis

Doctors diagnose infectious conjunctivitis by its symptoms and appearance. The eye is usually closely examined with a slit lamp (an instrument that magnifies the surface of the eye). Samples of infected secretions may be sent to a laboratory to identify the infecting organism by a culture. However, doctors usually do this only when the symptoms are severe or recurrent or when chlamydia or Neisseria gonorrhea is thought to be the cause.

What Is Pinkeye? Although most eye inflammations result in a pink discoloration of the eye (because of dilated blood vessels in the conjunctiva), doctors usually use the term pinkeye for conjunctivitis caused by infection with a bacteria or virus. One of the most severe forms of pinkeye is the result of infection with several particular strains of adenovirus. This infection, epidemic keratoconjunctivitis, is extremely contagious and often results in large outbreaks within a community or school. The infection is spread through contact with infected secretions. Such contact may take place person-to-person or through contaminated objects, possibly including doctors' instruments. The symptoms of this infection are similar to other types of viral conjunctivitis—redness, irritation, sensitivity to light, and thin, watery discharge. Many people develop a swollen lymph node in front of the ear on the affected side. These symptoms typically last from 1 to 3 weeks. Some people have blurred vision, which may last for weeks or months before resolving. Epidemic keratoconjunctivitis resolves completely without specific treatment. Doctors sometimes give corticosteroid drops to people with very blurred vision or severe sensitivity to light. Good hygiene, particularly hand washing, is needed to minimize the spread of the infection. Separate towels, washcloths, and bedding help minimize the spread to other members of the household. People generally stay home from work or school for several days or, in severe cases, even weeks.

Prognosis and Treatment

Most people with infectious conjunctivitis eventually get better without treatment. However, some infections, particularly those caused by some bacteria, may last a long time if not treated. Inclusion conjunctivitis may persist for months if not treated.

If discharge accumulates on the eyelid, people should gently wash the eyelid (with the eye closed) with tap water and a clean washcloth. Warm or cool compresses sometimes soothe the feeling of irritation. Because infective (bacterial or viral) conjunctivitis is highly contagious, people should wash their hands before and after cleaning the eye or applying drugs. Also, a person should be careful not to touch the infected eye and then touch the other eye. Towels and washcloths used to clean the eye should be kept separate from other towels and washcloths. People with infectious conjunctivitis generally stay home from work or school for a few days, just as they would with a cold. In the most severe cases of viral conjunctivitis, people sometimes stay home for weeks.

Antibiotics are helpful only in bacterial conjunctivitis. However, because it is difficult to distinguish between bacterial and viral infection, doctors sometimes prescribe antibiotics for everyone with conjunctivitis. Antibiotic eye drops or ointments, such as ciprofloxacinSome Trade Names
CILOXAN CIPRO
or trimethoprim-polymyxinSome Trade Names
, which are effective against many types of bacteria, are used for 7 to 10 days. Drops are applied 4 times daily. Ointments last longer and are applied every 6 hours but blur vision.

Inclusion conjunctivitis requires antibiotics, such as azithromycinSome Trade Names
ZITHROMAX
, doxycyclineSome Trade Names
VIBRAMYCIN
, or erythromycinSome Trade Names
E-MYCIN ERYTHROCIN
, which are taken by mouth. Gonococcal conjunctivitis may be treated with an injection of ceftriaxoneSome Trade Names
ROCEPHIN
. Corticosteroid eye drops may be needed in some people with severe adenoviral conjunctivitis, particularly in those in whom inflammation of the eye is interfering with important daily activities. Antiviral drops are not helpful for most conjunctivitis caused by viruses, with some exceptions. For example, a person with viral conjunctivitis caused by herpes may apply antiviral drugs to the eyes (trifluridineSome Trade Names
VIROPTIC
eye drops) or take them by mouth (acyclovirSome Trade Names
ZOVIRAX
).

Last full review/revision June 2008 by Mitchell H. Friedlaender, MD