Kabuto just needs a small sample of DNA then the Edo Tensei takes that form with the help of a human sacrifice.
Ithachi had his eyes when he died. They take the same form from when that person died.
Kishi's camera angles shows Anko simply laying there. Why would he give her facetime when Itachi, Sasuke, and Kabuto are about to fight?!
http://www.narutobase.net/manga/Naruto/578/11
Theory: I believe Itachi has deduced that waking her up or removing her from Kabuto's grasp is the first...