Concering the ' Tree of the Knowledge of Good and Evil ' their eyes became open?

It doesn't mean their actual physical eyes were opened, it means that their awareness was opened and now they knew they were naked. Before, they didn't know anything about being naked or needing to cover up body parts, they were innocent like a child is innocent and self consciousness did not exist. It wasn't until after they ate from the tree that all of that changed, which is precisely why God didn't want them eating that fruit!