DD (10) has been hit in the face with a ball whilst wearing glasses. It hurt the glasses more than her face, I think, but it wasn't comfortable.
However, she does have contact lenses - mostly because she does judo and can't wear glasses for that. She wouldn't be able to see the instructor demonstrate moves without the glasses.
Some opticians aren't happy about contacts for kids; others are. DD only has 15 pairs of daily contacts a month and only wears for 2-4 hours at a time.