Yah that and the fact the age differences. then again tsunade looks like 29 and she is like 99Lol @ Danzo=Obito.
Danzo's eyes have pupils, which Uchiha lack [It's all black, instead of having an Iris and a pupil] so there's no way he can be Obito.
And I looked at the picture, it looks pretty normal to me.
Madara is a little bit sleepy eyed, so his eyes are like half shut.
The drawing is to small to detail the whole thing, so he just drew the basic outline of an eye, something like this:
(o)<------Eye
And plus, both of the eyes look pretty similar, so if one eye is missing, the other eye must be missing as well, no?