It's enough to stare at anything for a few minutes without moving eyes to get similar effects and hallucinations. We see with good resolution only a small part

It's enough to stare at anything for a few minutes without moving eyes to get similar effects and hallucinations. We see with good resolution only a small part of our visual field. Perhaps the brain starts to "invent" what's there it we don't give it information by constantly moving eyes. As a more advanced version, they say that fire kasina practice may produce very interesting visual effects.