(a) I would encourage my friend to wear the glasses by telling him/her the side effects of not wearing it.
(b) I would ask him/her to wear the glasses everyday which would help him/her in proper vision and I would motivate my friend by telling him/her about the advantages of wearing it.

Listening depends upon how close you are with your friend but these suggestions should must be given: Wear your glasses regularly and if he or she doesn't then tell him the side affects.. His or her future depends on how he studies presently and for better studies we need a better eye sight.. Hope my answer was helpful..