>>2842733Sure, just weigh them to a separate bone parented to the "pupil" (iris) bone. You can use one of the bone duplicating functions (don't forget to edit and register the output) or add a bone based on selected vertices. You can also use vertex morphs. Be careful, though. Once you start doing such things, it's pretty hard to stop, and eventually you end up having to disable bone display when you want to adjust the line of sight or resort to using hidden bones inheriting rotation from visible handles away from the face.
Relevant video:
https://www.nicovideo.jp/watch/sm24205147 