Oh internets, You so silly!
I got hit right in the eye once from the most powerful thrower on their side. I couldn't see a damn thing for like ten minutes.
Me too, Right after it was batted, and it was one of those stuffty sharp plastic balls* that has holes in it so it cut the outside of my eye pretty badly. Couldn't see right for a few days.
Luckily it didn't damage my eye :p
*I couldn't find any images of it on google, I presume they don't exist anymore.