What Is Conjunctivitis?

An Overview of "Pink Eye"

What is Conjunctivitits
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Conjunctivitis, or pink eye, is an inflammation of the conjunctiva. The conjunctiva is a clear mucus membrane that lines the inside of the eyelid and covers the white part of the eye. Pink eye is a term commonly used to refer to all types of conjunctivitis. Pink eye is a fairly common condition, especially among school-aged children. Children are usually sent home from school if pink eye is suspected, as it can be very contagious and may spread quickly.

Pink eye rarely causes long-term vision or eye damage, but it can make the eye extremely red. There are several types of conjunctivitis. It is important to have an eye doctor evaluate the condition to determine proper treatment.


The most obvious symptom of pink eye is a red or "pink" colored eye. Inflammation causes small blood vessels in the conjunctiva to darken, resulting in a pink or red tint to the white of the eye. This inflammation is a sign of the immune system reacting to a foreign substance, irritation or invading organisms, such as bacteria. A case of pink eye may produce the following symptoms:

  • Redness in one or both eyes
  • Itchiness in one or both eyes
  • Blurred vision and light sensitivity
  • Gritty feeling in one or both eyes
  • Discharge in one or both eyes that forms a crust at night
  • Excessive tearing


Pink eye can result from the following, with viruses being the most common trigger:

Risk Factors

The biggest risk factor of pink eye is being exposed to someone infected with either the viral or bacterial form of conjunctivitis. Someone with conjunctivitis may be contagious for seven to 14 days after signs and symptoms first appear.


It is important for an eye doctor to determine the type of conjunctivitis you have, so appropriate treatment can be given. Your doctor will be able to pinpoint the type of conjunctivitis by asking questions and examining your eyes. The way your eyes feel will usually reveal what type of conjunctivitis you have:

  • Viral conjunctivitis: Viral conjunctivitis is associated with upper respiratory infections and colds. It usually affects only one eye, but can affect both eyes. Viral conjunctivitis causes excessive eye watering and a light discharge. Viral conjunctivitis is more common in children and tends to be much more contagious than the bacterial type. Viral conjunctivitis is associated more as true "pink eye."
  • Bacterial conjunctivitis: This type of conjunctivitis is caused by bacteria. Bacterial conjunctivitis affects both eyes and often produces a thicker, yellow-green discharge. It may also be associated with a respiratory infection or a cold. Bacterial conjunctivitis is more common in children than in adults and can be contagious. Some babies are born with a blocked tear duct that prevents tears from draining properly. This can also lead to bacterial conjunctivitis.
  • Allergic conjunctivitis:The allergic form of conjunctivitis is caused by a reaction to an allergen, such as pollen, or a foreign substance. Allergic conjunctivitis affects both eyes and causes itching and redness in the eyes and sometimes the nose (much like allergy symptoms). The eyes may also appear swollen and tear excessively. In severe cases, the conjunctiva may appear blister-like. The eyes may also have a white, stringy mucus discharge.
  • Chemical conjunctivitis: Chemical conjunctivitis causes redness and inflammation of the conjunctiva. It is caused by an irritant or an actual splash of a chemical into the eye, such as chlorine. The eye may produce clear mucus in response to the chemical agent. This type of conjunctivitis usually clears up on its own within about a day.
  • Papillary conjunctivitis: Sometimes referred to as giant papillary conjunctivitis (GPC), this type of conjunctivitis is caused by inflammation due to a foreign object in the eye. Papillary conjunctivitis can also develop from exposed sutures after having eye surgery. More commonly, GPC is caused by the constant presence of a contact lens. The eye may become red, and bumps may form on the eyelid. These bumps, called papillae, are often larger on the back side of the upper eyelid. GPC usually affects both eyes and causes contact lens intolerance, itching, a heavy discharge, tearing and red bumps on the underside of the eyelid.


    An accurate diagnosis can be made by your optometrist, ophthalmologist or pediatrician. Diagnosis of conjunctivitis is based on symptoms. The doctor may take a sample of tears to perform a test to determine the proper diagnosis. A bright microscope may also be used to examine the eyes in more detail. 


    Because there are many types of conjunctivitis, it is essential to let an eye doctor determine the appropriate treatment. Your doctor may prescribe antibiotic eye drops if the infection is bacterial, and the infection should clear within several days. Antibiotic eye ointment, in place of eye drops, is sometimes prescribed for treating bacterial pink eye in children. Viral conjunctivitis cannot be treated with antibiotic eye drops or ointment. Like the common cold, over-the-counter remedies may relieve some symptoms, but the virus will have to run its course. In the case of allergic conjunctivitis, your doctor may prescribe eye drops, such as antihistamines, to alleviate allergic symptoms.

    If you have been diagnosed with conjunctivitis, follow these tips to avoid spreading of the infection:

    • Wash your hands frequently.
    • Avoid rubbing your eyes.
    • Don't share washcloths, towels or pillowcases.
    • Don't share eyedrops or cosmetics.

    Conjunctivitis is usually a minor eye infection, but it can develop into a more serious condition. It is always best to seek the opinion of an eyecare professional.


    American Optometric Association, Conjunctivitis. AOA. 3 Jun 2007.