For once I won't fall for creating a continuation for the Orochimaru-Paedophile line .

I think I have kinda asked this before as well. If he was just after some visual enhancements he could have gone for the Byuakugan also or when he met Sasuke he could have just ripped his eye out and plugged it in.

Or maybe the reason why he didn't take Sasuke's eyes is simply that they are physically too small for him, since Sasuke is only about 12-13 his body is still growing. Maybe he would have taken his eyes though if he didn't feel Sasuke had the potential when he toyed around with him in the forest.

Maybe he is going to try and do an Emperor Palpatine thing and take control of Sasuke and make him is right hand man, and get rid of Kabuto at the same time!

As for using Sasuke to fight Itachi, Sasuke may be talented but I don't think it is realistic for a child to grow into some uber monster in a short space of time and he would have to train Sasuke himself for a while and maybe give him another seal on the other side of Sasuke's neck to give him the extra power that Orochimaru has been speaking of.