I'm thinking of smashing my sister's badly needed glasses.
That sounds like a horrible idea! I have to object to your plan against your sister.
Why would you do that?
As you said, your sister needs those glasses in order to function, and if you smash them, she will be unable to do most things until she gets a new pair. You shouldn't damage anyone's possessions intentionally as it will cause a lot of emotional pain and frustration. If your sister has been upsetting you, you should talk with her and try to resolve the issue constructively instead of destroying her things and worsening your relationship with her.
It's only some fucking glasses are you serious? What's the big deal with them anyway? She can take care of herself.
From the way you have described the situation, your sister will not be able to take care of herself, since she badly needs those glasses. And even if she didn't, you are still destroying a very expensive piece of property. This kind of behavior is not acceptable, and it will just invite retaliation from your sister, or trouble from your parents.