I'm looking for a short-short story where the narrator directly addresses the reader, describing a far future world where many people have retreated into dream worlds and forgotten they're dreaming, tells how they try to recover such people by inserting messages into their dream worlds, and then claiming the reader is one such person, asks the reader to please come back to reality.
At one point the narrator directs the reader to look for a code in the blind spot of their eye.
At the end of the story the narrator acknowledges that they're losing the reader's attention and resolves to let the reader slip back fully into their dream world.
I read this story a long time ago. I don't know how old the story was at the time, but it's certainly at least 10 years old.