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.