Well, it is normal to have this kind of symptom. Also, you should know that in some degree, it is a sign of black eye. Of course, it all depends if your eyes are hit and how hard the slap was. But from your description, the hit has caused the black eyes. As we know that, when your eyes are hit, it will make the blood around your eyes flow not so smoothly. And then it will turn black spots in your eyes. In other words, a black eye is the result of bleeding underneath the skin around your eye. For your situation, you can try some ways to relieve the symptom. You can put on ice on your eyes so that it can cool them. And remember that you should do this for several times. And, you need to be very careful when icing your black eye. The area around your eye is very, very sensitive, and it's already been infected by some other irritants. Anyway, just be careful about it.