There are fascinating descriptions of patient hallucinations after loss of vision in the aptly named book "Hallucinations" by Oliver Sacks. Tons of examples, b

There are fascinating descriptions of patient hallucinations after loss of vision in the aptly named book "Hallucinations" by Oliver Sacks. Tons of examples, but one that many musicians with partially lost vision experienced those missing parts of their vision randomly replaced by sheet music. Stare at sheet music your whole life, and your brain starts to predict sheet music anywhere. But when they tried to play the music, it didn't make sense. For those with complete loss of vision, the hallucinations became immersive, featuring complete scenes with people and events.