Well, in my opinion, if you are angry, it can lead to dilated pupils. Generally speaking, there are many factors which can cause dilated pupils. For example, high blood pressure can be the cause. When you are angry, your blood pressure can be high, and then it can lead to dilated pupils. And you also should know that when you are too tired, it is easy for you to have high eye pressure. When you have eye pressure, it can make the black part of the eye bigger than normal. And then it leads to dilated pupils. By the way, anxiety can cause it too. so just be careful about it.