Maybe you just got some kind of eye disease. Black eyes can be a starting sign of some kind of eye disease. We know that the skins under our eyes are very thin and tender. If the blood vessels in this area dilate, it can mean that there are some problems with the circulation of the blood in this area. You'd better see an eye doctor immediately. Good luck!
Well, I think you may mean that you have black circles under your eyes. Usually we won't have spontaneous black eyes. If you stay up too late in the night, you may have black circles under your eyes. Or you just get black eyes by hit on some foreign objects without even notice that. No matter black circles or black eyes, they can go away on its own few days later, you just need to relax and catch up enough sleep at the same time.