teded:Sometimes, against a uniform, bright background such as a clear sky or a blank computer screen
teded:Sometimes, against a uniform, bright background such as a clear sky or a blank computer screen, you might see things floating across your field of vision. These “floaters” are not any kind of external objects, nor are they alive. Rather, floaters are tiny objects that exist inside the eyeball, and cast shadows on the retina - the light-sensitive tissue at the back of your eye.To learn more about floaters, watch the TED-Ed Lesson What are those floaty things in your eye? - Michael MauserAnimation by Reflective Films -- source link