Yes, if the black eyes are got from the strong hit on the head, you may leave the great eye damage permanently because of the damage of the brain part. However, the common black eyes may be cured about half a month by the auto healing process in the body when you keep the good habit of life in sleeping and eating.
Well, generally speaking, as we know that black eye is caused by the injury to the eyes or the head and nose, so most black eyes are superficial injuries. And then you should know that they don't cause any permanent damage to the eye or to the tissues around it. So you should not too worry about it. But on the other hand, you'd better try some ways to heal it for the black eyes can be ugly and annoying. For the treatments, you can use warm cloth to compress your black eyes. Just do it everyday, it may relieve the symptom. Also, having a good rest is also effective.
Sorry to know that your eyes are bruised. Anyway, it does not matter. Well, as a matter of fact, the damage that bruised eyes could generate is changeable, which means that sometimes it could be very serious, leading to head concussion or some impairment of nervous systems in the eyes, permanent damage is possible . Typically, it would recover in a week or so, but if the situation remains bad, you should visit a doctor.