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.
Yes, the cold mat let you get the dilated pupils. When you get the cold, you may have weak immune system which may let your eyes get infection easily. Thus, your eyes may get dilated. You'd better use some eye drops with anti-inflammation to release the dilated pupils. Or you could treat the cold with medical care and then you will find that the pupil eyes will be disappeared.
Well, I can see that you are concerned about your eyes. Anyway, according to some cases, sometimes a cold, in theory, could lead to dilated eyes but that is not very serious. However, there might be other problems which result in your dilated eyes, because dilated eyes could be seen as a signal of health hazard. Anyway, you should try to pay more attention to your eyes, maybe you need an eye exam or overall exam.