I have pupils that are almost always fully dilated, regardless of the light and such, and I am an opiate user. When I do opiates, my eyes become pinned, and it's the only time that my pupils change, for the most part. That having been said, I've been high around my family, friends, and coworkers, none of whom know about my usage of opiates and they rarely notice anything. If they do notice that there has been a change in my eyes, they can't figure out just what that change is, they can only recognize that something is "funny" or different about the way I look at the time.
I wouldn't worry too much about other people noticing. The only people who have ever noticed the changes in my pupils are other users of opiates.