Is it normal to have vision flooded with patterns during a head rush?

I get a lot of head rushes. Sometimes they’re so bad that I have to hold onto something to not fall down. Anyways, whenever I get a head rush, my vision is flooded with dark green patterns, I can’t explain them. But basically I can’t see. There’s a lot of checker patterns, and a lot of whirly looking things. Everyone says that their eyes go out of focus but my vision is just completely obstructed by these weird grey-green patterns. Is that normal? Or is it usually just an “out of focus” thing?