On a lighter note...

It's important to remember that just because we are producing a device for blind/partially-sighted users, that is not just one well-defined section of society. The only thing we can take for granted is that the target audience will not be able to see very well.

There is no 'one size fits all' thing here, so we need to be just as thorough in investigating the needs of users as we would be if we were focussing on a device for sighted people. All blind people's needs and capabilities are different.

And of course, just like sighted people, some unfortunate people are handicapped with plain stupidity...

"Other disabled people make me cringe" (BBC Ouch)