Conjunctivitis (kuhn-juhngk-tuh-´vahy-tis) is an inflammation (swelling) or infection of the thin layer (conjunctiva) that lines the inside of the eyelid and covers the white part of the eye. Inflammation can cause blood vessels in the eye to become larger. And that can make the white of the eye look pink or red. Thus, conjunctivitis is often called pink eye or red eye.