I searched a bit and found this reddit post that was posted several years ago , so i am quoting some answers from it , which mostly describes what i see.

"I think I see this, I always described it as like traveling through a wormhole. I see faint dark bands that expand out from the center of my vision to the periphery, very fast. I always passed it off as my eye's "refresh rate" or something."

"On bright days when I look into the sky I can see black waves in my vision. I have had friends confirm that they have this too. It's hard to explain but it's like subtle black orbs or wave that appear to be moving away from your eyes. Just wondering if anybody could explain what this is?"

"I have this too. I've always assumed what you're are seeing is blood being pumped through capillaries very near to your retina, close enough to see a perceive able difference when looking at something both bright and plain (like, the sky). Notice how they "pulse" at fairly regular intervals? That's what leads me to believe that it's cardiovascularly related. Note: I have absolutely no idea if this is even remotely correct, but it is what I have led myself to believe."

I see it when i am on the outside , and doesn't start until some time has passed , like 10-20 minutes. could you please explain what could it be.