Viohazard broke his glasses while we were in NZ, not long after we got new ones in Japan, so we had a great

opportunity to compare NZ opticians with Japanese ones. You may be interested to know that glasses are no cheaper here in Japan, one way and another, even though it's the home of many famous lens brands. National health insurance doesn't cover glasses here either.
We discussed the music-reading issue with the optician, and they gave him a simple type of progressive lens. Usually if you tell the optician what you are having most trouble with, they will prescribe the strength of the lens to match that problem best.
The Japanese optician said that that it was best to underprescribe, not rely too much on glasses etc etc. The NZ optician said it just depended on how badly you wanted to see what you were looking at...but his old Japanese glasses and his new NZ glasses were almost identical in basic strength!
Viohazard can still read close things like books OK, but he has one other problem with reading music - visual tracking. He tends to move his head instead of just his eyes. When you move your whole head, your eyes often end up moving inaccurately (too far), so you skip phrases or lines. He's been practicing following one of those pencil with gimmicky monsters on the top of it with his eyes only. It was never much of a problem with reading books, because the lines are shorter and the book is closer to the eyes. If reading music is more of a problem than reading books, maybe check tracking too.
He wears his new glasses much more than he wore his old ones. I am not so sure that the glasses have made his sight worse, though maybe he's right - I think that maybe 1) he now notices when he can't see things clearly, and 2) apparently your eyesight often gets worse suddenly when you start growing taller at around age 12 (Viohazard will be 12 in January).