Immediate treatment for a black eye is ice and rest.
Ice helps reduce swelling by constricting the blood vessels and decreasing fluid accumulation. Apply ice or a cold compress to the eye for 15 minutes every hour for 24 hours. (Avoid pressing on the eye to prevent further bleeding or swelling.)
Keep the eye safe from further injury by staying away from strenuous activities or sports.
A medical evaluation by an eye doctor or primary care physician should be performed. A blow severe enough to cause a black eye can also cause a fracture of the part of the skull surrounding the eye, called the orbit. In addition, the floor of the orbit can be “blown out” causing an eye muscle to be trapped. A common complaint of an "orbital blow-out fracture" is vertical double vision. Furthermore, blood and fluid can seep through the break in the orbit, causing facial congestion. Medical evaluation of eye trauma should never be delayed, as serious eye conditions can worsen if not treated early.