Except for the strap, I come very close to agreeing with MM.
The honest truth is, I don't know that we'd have this situation, because I would have sat down and had a talk with Glenn at the very start. Looking back, I can see where I needed glasses from the time I was in first grade (only time I got in trouble in first grade was when I got out of my chair, while the teacher was out of the room, so I could read the overheard projector she was using instead of the blackboard). I always wanted to sit in the very front row at the movies, and no one ever questioned why. I was always told I was sitting to close to the TV. With all of that, no one ever asked why, and it never occurred to me to ask how the rest of them could see it from that far away.
I was also ten years old when I got glasses. They weren't comfortable at first, and I did get teases about them a little. Worse than that, I had no choice in the frames; I got the very cheapest pair they had available (thanks to my cheapass step-father). Despite the fact that he bought the cheapest pair he could, because he 'knew (I) was going to break them', and despite him bugging me not to read so much, I did get whipped when a pair got knocked off and stepped on while I was playing football.
Despite all that, it was worth it, because I could finally see the world. (The glasses also got rid of about 90% of my motion sickness problem).
I hope that I would sit down with Glenn, share those stories with him, and it would be enough to convince him that this is a good thing, and that he really needs to adjust. If anyone ever bothers him about them, I'll suggest letting them try them on. When they complain, he can point out that the way they see the world with the glasses is how he sees it without. Most people will leave him alone after that, and those that don't would find something else to tease him about anyway.
But deliberately breaking the glasses is going to get him a dose of the hairbrush.