What is "pink eye"?

Pink eye, or conjunctivitis, is redness and inflammation of the membranes (conjunctiva) covering the whites of the eyes and the membranes on the inner part of the eyelids. These membranes react to a wide range of bacteria, viruses, allergy-provoking agents, irritants, and toxic agents, as well as to underlying diseases within the body. Viral and bacterial forms of conjunctivitis are common in childhood, but they can occur in people of any age. Overall, however, there are many causes of pink eye. These can be classified as either infectious or noninfectious.

Viral pink eye

One leading cause of a red, inflamed eye is a virus infection. Adenoviruses are the type of virus that are most commonly responsible for the infection. Viral pink eye symptoms are usually associated with more of a watery discharge that is not green or yellow in color. Often, viral "cold-like" symptoms, such as sinus congestion and runny nose, are also present. The eyelids may be swollen. Sometimes looking at bright lights is painful. While viral pink eye may not require an antibiotic, those affected should see a doctor, as occasionally this form of pink eye can be associated with infection of the cornea (the clear portion of the front of the eyeball). This infection must be correctly detected and treated. Viral pink eye is highly contagious. The symptoms of viral pink eye are pronounced for the first three to five days after symptoms appear, with slow resolution over the following one to two weeks.

Bacterial pink eye:

Staphylococci and Streptococci, among others, are types of bacteria that commonly cause pink eye. Symptoms of bacterial pink eye include: eye pain, swelling, redness, and a moderate to large amount of discharge, usually yellow or greenish in color.
The discharge commonly accumulates after sleeping. Affected children may awaken most unhappy that their "eyes are stuck shut," requiring a warm washcloth applied to the eyes to remove the discharge. Bacterial pink eye is treated by repeated warm washcloths applied to the eyes (try applying these to your child's eye one eye at a time during a favorite video) and requires antibiotic eyedrops or ointment prescribed by the doctor.