Conjunctivitis

Conjunctivitis, also known as pink eye, is inflammation of the conjunctiva, the thin and clear layer that covers the white surface of the eye and the inner eyelid. It makes the eye appear pink or reddish. Pain, burning, scratchiness, or itchiness may occur. The affected eye may have increased tears or be stuck shut in the morning. Swelling of the sclera may also occur. Itching is more common in cases that are due to allergies. Conjunctivitis can affect one or both eyes.
The most common infectious causes in adults are viral, whereas in children bacterial causes predominate. The viral infection may occur along with other symptoms of a common cold. Both viral and bacterial cases are easily spread among people. Allergies to pollen or animal hair are also a common cause. Diagnosis is often based on signs and symptoms. Occasionally a sample of the discharge is sent for culture.
Prevention is partly by handwashing. Treatment depends on the underlying cause. In the majority of viral cases, there is no specific treatment. Most cases that are due to a bacterial infection also resolve without treatment; however antibiotics can shorten the illness. People who wear contact lenses and those whose infection is caused by gonorrhea or chlamydia should be treated. Allergic cases can be treated with antihistamines or mast cell inhibitor drops.
Between three and six million people get acute conjunctivitis each year in the United States. Typically they get better in one or two weeks. If visual loss, significant pain, sensitivity to light or signs of herpes occur, or if symptoms do not improve after a week, further diagnosis and treatment may be required. Conjunctivitis in a newborn, known as neonatal conjunctivitis, may also require specific treatment.