I"m so sorry he's resisting the glasses. I agree with the person who posted that if he was fine with them at home but suddenly saying he won't wear them at school, he probably is fearing teasing. You and he need a calm and reassuring talk about this, and you need to get him to talk about whether he just thinks he'll be teased or whether he actually has heard and seen kids being teased for wearing glasses. If it's the latter - I'd involve the teacher right away because she or he needs to have some talks with the whole class about behavior. But also...my daughter was thrilled to wear glasses to school because SO many kids already had them. He may not have realized how many kids he knows do have glasses; he may be so used to seeing them in their glasses that he doesn't really register it, and if you know he has classmates in glasses, you could could remind him of that. Does he have any friends with glasses? Could you get their parents to have them talk to him about it?
This is going to pass, by the way. He will realize that he is not seeing the board, is having trouble reading, can't see the ball in gym class, etc. and he will realize at some point that he needs glasses.
He does also need GLASSES and not just contacts as you note. Even if he gets contacts, there will be a lot of time he is in glasses -- at his age they are probably not going to give him 24/7 contacts he wears for a week all the time. So, yes, he does need to cope with the glasses not just until he gets contacts but forever. And be aware -- it's always possible he may not be a candidate for contact lenses, or at least not yet, so I would not build up the idea of "You'll have contacts soon" in his mind in case the doctor says it's not right for him.