Usually, what causes the dilated eyes is that the neurological input to the constrictor muscle is blocked temporarily by the chemicals you have put into your body. So if you want to undilate your eyes, you should wait until your body metabolizes the chemicals to a normal state, and your eyes will recover themselves. While you want to undilate your eyes in a fast way, there are three ways may help you. First, some prescription eye drops that contain phenyephedrine and pilocarpine are recommended, you can go and consult an oculist. Second, you can wear coloured-contacts that can constricts pupils. Third, you can stay in a brighter place to undilate your eyes faster. In all, if you really suffer from a dilated eyes, the healthy way is to wait until it undilated by themselves.