Nothing.
Blindness is the absence of sight. There is no darkness, or shadow, or whatever you come up with in an attempt to understand how a blind person “sees”. There’s just nothing.
When you close your eyes, you can still perceive light and shadow which is what a large portion of blind individuals “see”. According to Vision Aware, only 15% of people are fully blind or NLP (no light perception). Think about a scene happening behind you. With no eyes on the back of your head, you’re left with only the information that you can hear and maybe touch until you turn around.
Most people don’t think too deeply about vision. A blind person sees shadows, and visually impaired means you just haven’t tried glasses yet. But once you get past 20/20, vision corrected by glasses and totally blind, you realize that a person’s vision can vary greatly. Fully blind, light perception, tunnel vision, usable vision but unable to read print, glasses but not corrected enough to not be legally blind, blind in one eye, etc. Vision is on a spectrum.
A person doesn’t have to look visually impaired (i.e., have filmy eyes or a squint) to be blind. I mention that because many people have been disbelieving of, or even rude to my visually impaired friends asking for assistance. They neither look blind nor wear glasses, so why can’t they just read the sign? If it isn’t too far for the sighted person to see it, then the VI person should see it too, right? When my friend tells them that they’re visually impaired, and can see the sign, yes, but not read it from that distance, some people don’t believe them. Most do, but some seem to have an issue with assisting someone who looks “normal”. It’s as though they have to be able to visually perceive the disability for them to feel good about themselves, or like they did a good deed.
On the opposite end of the spectrum, I get people not believing that I can see because of the filmy look of my eyes. In elementary school, my peers would challenge my claim by asking me to tell them how many fingers they were holding up. Now, I’ve gotten people asking if I can see something, or what color something else is. It doesn’t happen very often now, but it does happen. Though now I no longer care about proving anything to anyone. I know what I can see, and you’re probably a stranger to me, so why should I go out of my way to have you believe me?
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With all of that said, you should keep in mind that sometimes a visually impaired person will use the terms interchangeably. I do. And I have some usable vision. Sometimes it’s just easier to say that your blind rather than trying to explain that it’s hard for me to describe what I can/can’t see. No, I don’t see shadows. Or not in the way you probably mean. I can see light, color, shapes but so can you (presumably). My vision has worsened over the years: I can no longer read money, not see as far, but I never know how to describe what I do see.
How would you describe your vision?
Once you’ve figured that out, you should check out my latest mended misconception, on echolocation.