What Is a Black Eye?
In some cases, however, a black eye is a warning sign of more serious injury to the eye or to the skull. Any damage to the eyeball that causes it to become red and swollen must be promptly evaluated by a doctor or an eye specialist. Blunt force eye injuries, as happens in fighting, competitive sports, and ordinary accidents, could involve an unsuspected detached retina, internal bleeding, or other serious problems. An orbital fracture involving one of the five delicate bones around the eye may trap an eye muscle or soft tissues. A fracture could also damage the optic nerve and permanently damage eyesight. If so, emergency surgery may be required to correct the condition.
What Causes a Black Eye?
Most black eyes are the result of blunt trauma that causes bleeding beneath the thin eyelid skin, producing the characteristic black and blue discoloration. A fracture deep inside the skull can also blacken both eyes, even though the eye area itself was not injured. People with sinusitis from allergies sometimes get "allergic shiners" -- darkening under the eyes caused by inflamed and engorged blood vessels -- but this is not the same thing as a black eye, which is caused by an injury.