Yes, drugs can open your pupils wider than they would by themselves. I've seen special eyedrops sold for astronomy. They're probably atropine based or hopefully something related, but safer.(??) Atropine is the main toxin in deadly nightshade and was used as a beauty product in 18th/19th century: to make ladies' eyes' pupils bigger and supposedly more attractive - though it probably made them look more like they're tripping off their heads...
https://www.youtube.com/watch?v=BceHGzsDVLY&t=1m26s