You don't have to be visually impaired to have that kind of stuff happen.
When we were building my house, my brother-in-law had a piece of plywood covering a hole in the loft floor. One of his helpers went around neat nicking, picking up scrap pieces of wood; when my brother-in-law stepped backwards, he ended up in the living-room on top of the wood stove wondering what happened to the plywood he had covering that hole.
Same sort of thing happened once when I was at a neighbor's house and walked into a closet which had no floor, and I fell down to the first level of the house! (the house was still being built... very odd, now that I'm thinking of it.) The kids' mother just said "Honey, I'd rather you guys didn't play down here." and sent me on my way. No one knew I'd fallen. I went home with my concealed scratches, without telling anyone, and got scolded for being over there in the first place!