Conjunctivitis (also called pink eye or madras eye)  is redness and inflammation  of the conjunctiva (the outermost layer of the eye and the inner surface of the eyelids).

Pinkeye has a number of different causes, including:

Viruses
Bacteria (such as gonorrhea or chlamydia)
Irritants such as shampoos, dirt, smoke, and pool chlorine
Allergies, like dust, pollen, or a special type of allergy that affects some contact lens wearers
Pinkeye caused by some bacteria and viruses can spread easily from person to person, but is not a serious health risk if diagnosed promptly. Pinkeye in newborn babies, however, should be reported to a doctor immediately.

Symptoms

The symptoms of pinkeye differ based on the cause of the inflammation, but may include:

Redness in the white of the eye or inner eyelid
Increased amount of tears
Thick yellow discharge that crusts over the eyelashes, especially after sleep
Green or white discharge from the eye
Itchy eyes
Burning eyes
Blurred vision
Increased sensitivity to light
See your eye doctor if you have any of these symptoms of pinkeye. Your eye doctor will conduct an exam of your eyes and may use a cotton swab to take a sample of fluid from the eyelid to be analyzed in a lab. Bacteria or viruses that may have caused conjunctivitis, including those that can cause a sexually transmitted disease or STD, can then be identified and proper treatment prescribed.

Tretment

The treatment for pinkeye depends on the cause.

Bacteria. Pinkeye caused by bacteria, including those related to STDs, is treated with antibiotics, in the form of eye drops, ointments, or pills. Eye drops or ointments may need to be applied to the inside of the eyelid three to four times a day for five to seven days. Pills may need to be taken for several days. The infection should improve within a week. Take or use the drugs as instructed by your doctor, even if the symptoms go away.

Viruses. This type of pinkeye often results from the viruses that cause a common cold. Just as a cold must run its course, so must this form of pinkeye, which usually lasts from four to seven days. Viral conjunctivitis can be highly contagious. Avoid contact with others and wash your hands frequently.

Irritants. For pinkeye caused by an irritating substance, use water to wash the substance from the eye for five minutes. Your eyes should begin to improve within four hours. If the conjunctivitis is caused by acid or alkaline material such as bleach, immediately rinse the eyes with lots of water and call your doctor immediately.

Allergies. Allergy-associated conjunctivitis should improve once the allergy is treated and the allergen removed. See your doctor if you have conjunctivitis that is linked to an allergy.