I think the circular particles you saw called floaters, floaters are small bits of virtuous that get in the retina and appear in your vision. Over 70% of the population have floaters and they are usually harmless, however a sudden increase is an event to seek medical attention.
I guess there might be something wrong with your eyes or head. Sweetie, did you get beaten by something? That might be some kind of side effect cause by trauma or eye injury. So I suggest you to have your eyes checked immediately. Good luck!
We can see nothing after we close our eyes. Circular particles? They are real objects or just images? Sometimes we can see circular particles after we look directly into the sun. But this image will disappear a few seconds later.