Pink eye is an inflammation or infection of the conjunctiva, the transparent membrane lining the eyelid and part of the eyeball. It is the most common type of eye infection and is most likely to affect preschool-age children. Pink eye is also known as conjunctivitis.

Bacterial and viral infections are often the cause of pink eye. People may become infected after coming into contact with the tears or discharges from the eyes of an infected person. People with pink eye who also have an upper respiratory infection can spread the illness through droplets that are disseminated when coughing or sneezing.

Pink eye also can develop from noninfectious sources, such as allergies, foreign objects that become lodged in the eyes, and exposure of the eye to a chemical or other irritant (e.g., shampoos, dirt, smoke, pool chlorine).

Symptoms of pink eye usually appear anywhere from a couple of days to a couple of weeks after the person has been exposed to the source of the illness. People with pink eye may feel like they have something stuck in one or both eyes. As blood vessels in the conjunctiva swell, a pinkish tinge may develop in the whites of their eyes, which gives the condition its common name. Discharge from the eyes also is common.

Because infectious pink eye is highly contagious, people who have symptoms of this illness are urged to seek prompt medical attention. There is no treatment available for viral pink eye other than to let the virus run its course. Antibiotics may be prescribed to treat bacterial pink eye and can clear the infection in just a few days.

The best way to avoid pink eye is to take precautions against factors known to cause conjunctivitis. This means avoiding close contact with people who have viral or bacterial pink eye. People who are diagnosed with infectious pink eye are urged to remain home from school or work until at least 24 hours after treatments have begun or drainage from the eye has stopped.

Pink eye is an inflammation or infection of the conjunctiva, the normally transparent membrane lining the eyelid and part of the eyeball. Also known as conjunctivitis, it may affect one or both eyes.

Pink eye is the most common type of eye infection and occurs frequently in the United States. People of any age may develop pink eye. However, preschool-age children are at higher risk for pink eye than people in other age groups.

There are several different forms of pink eye, which may be infectious (e.g., viral, bacterial) or noninfectious (e.g., allergic or the result of reaction to irritant or injury) in nature. This topic focuses mainly on the infectious forms of pink eye.

Bacterial and viral infections are often at the root of pink eye. People may become infected after coming into contact with the tears or discharges from the eyes of an infected person. People with pink eye who also have an upper respiratory infection can spread the illness through droplets that are disseminated when coughing or sneezing.

Viral infections are the chief cause of pink eye, with adenovirus being the chief culprit. This form of pink eye tends to be spread through exposure to contaminated fingers, swimming pools and medical instruments. Many patients who develop viral pink eye have an associated upper respiratory tract infection. Incidence of viral pink eye tends to be highest in the late fall and early spring.

Less commonly, bacterial infections also may cause the illness. These infections usually stem from bacteria such as Streptococcus pneumoniae and Hemophilus influenzae (which tend to affect children), or Staphylococcus aureus (which tends to affect adults). The sexually transmitted diseases chlamydia and gonorrhea also can cause pink eye in people who touch an infected person’s genitals before touching their own eye. Pregnant women who have these sexually transmitted diseases while giving birth may transmit pink eye to their newborn infants. Bacterial infections are more likely to occur in the winter and spring.

Both viral and bacterial pink eye often are associated with colds and are highly contagious. People may become infected through close contact with some who has pink eye. In addition, pink eye can be spread when people touch a contaminated object before touching their own eyes, nose or mouth. Pink eye may occur in one or both eyes. It commonly begins in one eye and spreads to the other when the patient touches or rubs their eyes.

Pink eye also can develop from noninfectious sources. Allergies also are a frequent source of pink eye. This occurs when the body has an allergic reaction to an allergen such as pollen, mold or dander. Pollen is the primary allergen that triggers allergic conjunctivitis.

Other potential causes of pink eye include foreign objects that become lodged in the eyes, exposure of the eye to a chemical or other irritant (e.g., shampoo, dirt, smog, smoke, pool chlorine). Fungi and parasitic agents also can cause pink eye. However, this is uncommon.

Children who are born with an incompletely opened tear duct may also develop pink eye. This is because tears are needed to protect the conjunctiva by diluting bacteria and washing it away. Tears also contain enzymes and antibodies that kill bacteria.

Symptoms of pink eye usually appear anywhere from a couple of days to a couple of weeks after the person has been exposed to the source of the infection. People with pink eye often feel like they have something stuck in one or both eyes that cannot be removed. As blood vessels in the conjunctiva (membrane lining the eyelid and eyeball) swell, a pinkish tinge may develop in the whites of their eyes. Discharge from the eyes may crust over during sleep, causing the eyes to feel like they are pasted shut upon awakening.

In some cases, vision may be affected. Pus that slides across the eye can cause visual distortions, although sharpness of vision usually is unaffected.

Other symptoms associated with pink eye include:

• Blurred vision and sensitivity to light
• “Gritty” feeling in the eye
• Itchiness or pain in one or both eyes
• Increased tearing

The symptoms of pink eye may vary depending on the source of the infection. For example, viral conjunctivitis typically causes eye discharge that is watery or mucus-based. Meanwhile, bacterial conjunctivitis causes a thicker, yellow-green discharge accompanied by a respiratory infection and sore throat. Also, viral conjunctivitis frequently affects only one eye, whereas bacterial conjunctivitis tends to affect both.  Ear infections also are common in those who have bacterial conjunctivitis.

Itching is the chief symptom that accompanies forms of conjunctivitis caused by allergies.

Because infectious pink eye is highly contagious, people who have symptoms of this illness are urged to seek prompt medical attention. In addition, the symptoms of pink eye are similar to those of serious sight-threatening eye illnesses, such as acute glaucoma, uveitis and endophthalmitis. It is important to rule these conditions out before making a diagnosis of pink eye.

In diagnosing pink eye, a physician will perform a physical examination and compile a thorough medical history. Samples of eye secretions may be obtained and analyzed in a laboratory to determine the nature of the infection. Other tests that may be performed include measurement of a patient’s visual clarity, slit-lamp examination (microscope that studies the front of the eye) and tonometry (measures pressure inside the eyes).

Children with pink eye that does not appear to be the result of viral or bacterial infection may undergo allergy testing. If the patient is a child, a physician may look for the presence of a partially opened tear duct.

There is no treatment available for viral pink eye other than to let the virus run its natural course. This can take around two to three weeks, with symptoms typically becoming less severe over time. In the meantime, patients can relieve symptoms by applying warm compresses to their eyes. This involves dipping a clean, lint-free cloth in warm water and wringing it out before applying it gently to closed eyelids. Lubricating the eye with artificial tear drops also may help relieve discomfort.

Antibiotics may be prescribed to treat bacterial pink eye, resulting in a clearing of the infection in just a few days. These medications typically come in eyedrop form, although ointment is sometimes the preferred option in treating young children. Oral antibiotics may be used as well. It is important to continue to use the full course of medication even after the infection clears. Failure to do so may cause a recurrence of the infection.

Several medications are available to treat allergic conjunctivitis, including antihistamines, decongestants, mast cell stabilizers, steroids and anti-inflammatory drops.

Conjunctivitis that occurs as the result of an irritant typically is treated by flushing the eye with clear water repeatedly until the irritant is washed away. After this is accomplished, symptoms should begin to clear within a few hours. For all types of conjunctivitis, patients should avoid wearing contact lenses until the infection has cleared.

The best way to avoid pink eye is to take precautions against factors known to cause conjunctivitis. This means avoiding close contact with people who have viral or bacterial pink eye. People with viral pink eye may be contagious before symptoms appear, while people with bacterial pink eye usually become contagious once symptoms appear.

People who are diagnosed with infectious pink eye are urged to remain home from school or work until at least 24 hours after treatments have begun or drainage from the eye has stopped. People with pink eye are urged to wash their hands frequently and not to touch or rub their eyes with their hands. This will help prevent the spread of the infection.

Other tips for helping prevent the spread of pink eye include:

• Do not share towels and washcloths with other people, and change these items daily.
  
  
• Change pillowcases often and do not share them with others.
  
  
• Do not allow others to share a computer keyboard until pink eye is resolved.
  
  
• Discard eye cosmetics after an eye infection, and never share these products with others.
  
  
• Do not swim until the pink eye infection has cleared.
  
  
• Follow a physician’s advice on proper contact lens care.

People with allergic conjunctivitis are urged to avoid the allergens that trigger their condition. Using precaution when working with chemicals or objects that may become airborne can help reduce the chances of getting pink eye that develops from an injury to the eye.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to pink eye:

1. How will I know if I have pink eye and not a mild irritation of the eye?
   
   
2. What methods will you use to diagnose my pink eye?
   
   
3. What is the likely source of my pink eye?
   
   
4. What are my treatment options?
   
   
5. Should I stay home from work or school for a given period of time?
   
   
6. Should my family members be tested for pink eye?
   
   
7. Are there certain items I should wash or throw away to prevent re-infection?
   
   
8. How long am I likely to be contagious?
   
   
9. Am I at risk for certain complications related to my pink eye?
   
   
10. How can I be sure that my baby will receive the antibiotic necessary to prevent ophthalmia neonatorum?