Conjunctivitis, a condition many people refer to as "pink eye," affects the outer layer of the eye and the inside lining of the eyelid. The condition causes inflammation in these tissues, often resulting in redness, itching and irritation. Eyelids may swell and the eye may water or have a thick discharge. Knowing some of the causes of conjunctivitis may help prevent occurrence, as well as help determine available treatments.
Allergies
Pink eye may affect one or both eyes. If a person has symptoms of the condition in both eyes, allergies may have caused conjunctivitis, says the University of Maryland Medical Center. Many people with seasonal allergies commonly have pink eye when allergies flare. Contact with pet dander or other environmental allergens may also cause a reaction. Pink eye caused by allergic reactions will often respond quickly to allergy eye drops. Some forms of the drops do not require a prescription, and a person can find them in most pharmacies. People who have more significant allergic responses may require a prescription eye drop. As well, oral allergy medications may also help improve symptoms.
Bacteria
Bacterial conjunctivitis typically stems from bacteria on the body, says the American Optometric Association. A person may have the bacteria on her skin from coming into contact with another person who has the bacteria. To avoid pink eye from bacteria, a person should not rub or touch her eyes until she washes her hands, and she should never share makeup with another person. Eye doctors often prescribe an antibiotic eye drop to help relieve symptoms and improve the condition. However, in mild cases, bacterial conjunctivitis will often improve on its own. Newborns can have bacterial pink eye if the baby came through the birth canal and the mother carried a sexually transmitted disease such as gonorrhea or chlamydia. The condition requires immediate treatment to avoid permanent vision damage.
Viruses
The cold virus commonly causes viral conjunctivitis. The virus can spread through the body, but may also result from contact with another person who has the virus. The virus form of pink eye does not respond to antibiotics, and many eye doctors may recommend allowing the virus to gradually improve on its own. However, the doctor may prescribe an antiviral mediation to ease symptoms and inflammation.
