Black eye is a phrase used to describe bruising around the eye due to an injury to the face or the head. Blood and other fluids collect in the space around the eye, causing swelling and dark bruising in the tissue.

When there is trauma or injury to the face, the skin around the eye — which is very loose — is one of the first places to swell as fluid builds up. Although the name “black eye” would indicate otherwise, the eye itself is usually not injured. Many black eyes heal on their own in a few days.

However, a black eye can be a sign of a more serious injury. For instance, if there is bleeding within the eye that is called a hyphema and should be looked for any time you see a black eye. It can affect your cornea and your vision. In some cases of face or eye trauma, increased pressure inside the eyeball can occur, resulting in damage to the eye and eyesight if not treated. If both eyes are black after a head injury, it could signify a skull fracture or other serious injury.