Well, generally speaking, cold can lead to dilated pupils. And first, you should know that dilated pupils occur, when the pupils, the black part of the eye are bigger than normal. Also, we can say that dilated pupils look like a big black circle. And of course, many different factors can cause pupils to be dilated such as the high blood pressure and anxiety. So when you get cold, it is possible for you to have high blood pressure. In this way, it will increase the risk of getting dilated pupils. So you need treat your cold first. Besides, drug use, illness, and trauma are other causes. So you should pay attention to them.