Generally speaking, when people are in their adolescence, their pupillary distance will change with their age. But once becoming an adult, a person's pupillary distance will not change any more. Not like prescription which may change owing to various factors, pupillary distance of adults will always remains the same. If you are an adult, and you have your pupillary distance measured recently again, but you find it different with the number that your pupillary distance used to be, the probable reason is the error in measurement. For more information about pupillary distance such as how to measure a person's pupillary distance, you can refer to the following web site.
Yes, it will.
As you grow older, your face gets wider and longer, your eyes stay the same, so the position where your eyes are changed. Therefore, the pupillary distance changes over time. Normally, the pupal distance gets wider as you grow older. The situation will be more obvious, if you use your eyes very often, like reading, watching TV or looking at computers very often.
It may change over time. The pupillary distance of myopia eyes with strong prescription can change too But the distance will not change a lot. Usually it is changed within 1mm. By the way, I'd like to tell you something about the pupillary distance and the choosing of glasses. To choose a proper pair of glasses, the pupillary distance should be accurate. For the inaccurate pupillary distance may lead to the unsuitable frame and then it will influence the correction of vision. Usually, it is hard to choose glasses if the pupillary distance is small. Then if the pupillary distance is too big, to shorten the pupillary distance on look, people can choose the kind of glasses with dark frame and without decoration on it.