Okay, here we are back to where "words matter."
"Legally blind" does not mean that a person has had any interaction with any lawyers. Legally blind means that a person has worse than 20/200 optical acuity in either or both eyes with correction--that is, no matter what contacts or glasses you slap on them, that's all she wrote. I have 20/200 vision without correction; even without my glasses or contacts I can get around pretty well, but it would make life pretty hard to deal with it on a day in/day out basis.
"Blind" refers to a total loss of eyesight; however, the blind person might detect some real or imagined light at the edge of their field of vision. The reason so many blind people wear dark glasses (or at least one reason) is to deal with this residual light detection, which can be distracting at best.
"Visually impaired" is typically used to refer to someone who is not blind or legally blind, but who has poor vision even with correction; however, all people who are blind or legally blind are also visually impaired.
A purblind bird is visually impaired, not legally blind, since we have no way of knowing if their visual acuity exceeds 20/200 with correction.
Honestly, words really do matter.