Yea opiates may do it.. I'm not sure why you'd want to?.
Idk personally I love looking I'm the mirror every now and then and seeing no color left. Lol.
You really don't want to be messing with opiates just to get your eyes looking less bug eyed. MDMA + opiates in general isn't the best of ideas unless you have significant experience with both. You could try weaker OTC opiates like codeine, but I doubt a small dose of Codeine will be enough to fix your eyes.
He or she probably needs to hide their huge pupils from some one. I was always looking for ways to hide my eyes when I was around my parents or certain people. I'm pretty interested on this subject
I take hydrocodone every day for a medical condition and my pupils are still huge when I roll. I'm not sure if it would be the same with others, but it's been the same every time I've rolled, huge pupils that don't return to normal until I've slept.
I understand the theory though, but rapid pupil constriction on opiates is usually a sign of overdose. They can make your pupils naturally a little smaller, but nothing noticeable from what I've seen.