When you are shocked or surprising, you may get the dilated pupils. The pupils may become bigger. When you see something that you are interested in, you could also get the dilated eyes. These symptoms are normal. However, if you smoke and drink too much, you will also find that your eyes get dilated. However, this symptom is not normal which will be bad for your eye vision.
It is normal, very common situation. Pupil works just like the camera aperture, which functions to control the light into our eyes. If you are standing in the strong sunshine, your pupil will shrink to let less light into eyes. If you are standing in a dark environment, your pupil will dilate to let more light into eyes, so that you could see clearer. This is the way how pupil functioned. Sometimes strong emotion changes will cause the pupil dilated too, for example, angry, and extreme fear. It is common situation, so no need to worry about it.
Hello, actually your pupils are tiny holes that can let in light to your eyes so that you can see something clearly. But the amount of light get into your eyes is fixed, too much light or too little light can both be harmful to your eyes. So in low light areas, your pupils will get bigger to bring in more light so you can see better. But if the light is strong, your pupils will get smaller, otherwise you can not see clearly through the glare. In a word, your pupils help adjust the light that you need to see with through changing sizes.