Part 3 - Page 52 - Sketch (Patreon)

So blind people's eye muscles sometimes atrophy, and it causes their eyes to wander and they become strangely cross eyed. The fact that Toph is able to look straight ahead proves that the muscles that control how her eyes move works. I think that Toph's parents would have been the type to hire someone to train their blind daughter to "look" at people to be polite. However, she rarely does that, because she's Toph. Remember that episode where she attends a ball and says before hand "I know how to act, I just choose not to."