Toddlers, Anatomy, Jobs and Chaos!

Last night, my toddler stabbed my daughter in the eye with a steak knife. I got a hysterical text message at 6:30 p.m. (in the middle of class) about it. I, of course, packed up my shit and left to go home and check on her. The doctor says she is fine but the eye has been bugging her tremendously. 

My toddler is constantly doing uber-destructive shit like this to his little sister. He's poked her in the eye before but with a much less sharp instrument: a screwdriver. What do I do?! I know he's a jealous, curious, adventurous (and many other -ous's) toddler but he's either going to a) kill his sister or b) blind her. These things happen in the blink of an eye... er, no pun intended. It's not as if they are running around unsupervised. We have this house on lock down most of the time. We are the baby-proofingest parents ever! But sometimes, a knife gets left out and slides under the couch (thanks, honey.) Or sometimes, I have to rush to get ready for school and walk away for five minutes.