The name refers to the dark-colored bruising which is the result of accumulated blood and fluid in the loose areolar tissue following a blow to the head.

This blood tracks freely under the scalp producing a generalised swelling over the dome of the skull but cannot pass into either occipital or the temple regions because of the bony attachments of the occipitofrontalis muscle.

[1] If injury is more extensive, potentially even a skull fracture, an apparent black eye can sometimes worsen and may require professional medical treatment before it will resolve.

Though disfiguring, the vast majority of black eyes are not serious, require little or no treatment, and will resolve spontaneously within a week or two.

Blunt force or trauma to the eye socket results in burst capillaries and subsequent haemorrhaging (hematoma).

[2] The appearance (discoloration in purple and blue along with swelling) does not usually indicate a serious injury, and most black eyes resolve within a week.