Liss Blind?

How the hell is Lissandra blind? Part of her lore is that she's been impersonating people for generations. Even if she felt every part of their body, and knew what they looked like physically, there's still all of these minor things she'd have to actually see, like eye color, hair color, skin tone, that people would definitely notice if it were off. Equal opportunity league aside, it just doesn't make much sense.