Blindness comes in many different forms. It's not about your vision being blurred or completely dark. Some blind people can only see clearly through tiny slits or pinholes in their vision.

Imagine a sheet of paper that you poke maybe 2 or 3 small holes in, then hold up a few inches from your face. Those holes are all you can see through in your field of vision; the rest is obscured.

And then there are people who need bottle-lensed glasses just to be able to barely read large 100-pt text in front of their face. They're considered blind, even though they have some vision.

My mother had a Polish friend from her work who was like this. He had insanely thick glasses and walked mostly without a cane in familiar areas, but would have to touch your face to gauge your reaction while talking with you. Or practically press his face up against yours to look you in the eye. He had a laptop that would scan documents and display them in massive font so he could read them on the go.

Also, one of my best friends in high school woke up blind one day. His corneas detached from his eyeballs; a genetic defect from his family. He didn't wake up in a dark room, he could still see shapes and colors. But he couldn't focus on any of them.

I was tasked with walking him to each of his classes in school, because I had experience leading the blind. His greatest annoyance was when people waved their hand in front of his face and asked if he could see it. When he flinched (because a large blurry object came at his head), they accused him of faking blindness because he saw them. But he couldn't make out what was coming at him, he was just reacting to sudden movements near his face.

My friend eventually got corneal transplants, which restored most of his vision. But he can never drive a car because his vision isn't good enough to read road signs, even with corrective lenses. He's considered legally blind.

When you need to split hairs, blind folks will call themselves "legally blind" if they have some limited sight, or "totally/completely blind" if they have no vision whatsoever. But if your optometrist claims you qualify for legally blind, you're generally considered blind amongst their community and qualify for any associated disability benefits that come with blindness.