In reality, it could go away as time goes by. But it is better for you to take some actions to help it heal up faster. Seeing a doctor is one of them and it's fast and effective. However, if the situation is not very serious, you can relieve it by some home remedies. For example, give some compress to your black eye with warm and wet cloth for several minutes per day. Or you can place teabag on the eye because the tannic acids help the circulation of the blood. In addtion, vitamin D is an effective solution to help blood vessel. You can eat some food rich in vitamin D, like bananas, spinach, oranges, etc. Neverthless, if the symptom still exist, it is not too late to receive a medical treatment.