You've hit on a topic I have been giving a lot of thought lately. I will try to limit my preachiness.
(Stepping on to my soap box)
To people outside of the community I either say that:
* I am a partially sighted blind person, or
* I am blind with some ability to see in the right conditions
After that, I may go into more detail if someone asks, they sound like they really want to know, and I have time and am feeling generous. Otherwise, it would be hard for me to care less about their opinion.
I never say I am legally blind, visually impaired, or have low vision. Call it a personal quirk of mine that I may write about one day.
I worked my way through college as a sign language interpreter. Often spending considerable amounts of time with some of the more activistic members of the deaf community. My views on what it means to be blind are, in large parts, influenced by my experience there as well as reading
$1 by Kenneth Jernigan of the NFB shortly after discover my vision loss.
To me:
>Anyone that must predominately use nonvisual tools and techniques to perform basic living tasks that people typically use sight to perform is blind.
Period. There are no other criteria for me. To further distinguish between ourselves within the community can help us where it allows us to better understand one another. However, allowing outsiders to do so, only serves to divide us, weakening our ability to support each other, and lessening our power.
(Stepping off of my soap box)
If you are in the US acuity is not the only criteria for legal blindness. Constricted visual field, sometimes known as tunnel or pinhole vision, can be as well.