OMG, what can I do before she pokes the baby's eye out?

Ok, I have an adventrous 4 yr old. I also have a 3 week old. My 3 week old has hezel-green eyes and my 4 yr old has light brown eyes. This morning she asked me why she had brown eyes and not green eyes. I told her b.c everybody is different and that is the way god made up. So I am in the kitchen washing my hands and the baby and my toddler are in the living room which is fully visible from the kitchen. So all of a sudden I hear the baby shriek. I look up and my 4 yr has her finger in her eye. I yell at her and tell her to leave the baby alone. This is like the 4th time she has done this. I told her to stop but she does not. She keeps saying "Mommy , I wanna touch her pretty eyes". The funny thing is she use to do this to my mother in law also who has green eyes. The only reason she stopped is b/c my mom in law gave her a . My husband tells me that is what I have to do but I just can not her. I also do not allow my husband to hit her b.c he is a man and could hurt her. What else can I do?