Eye floaters appear as black or grey specs, strings or cobwebs that shift around when you move your eyes and appear to dart away when you try to look at them directly.
Eye floaters are caused by changes that occur as the jelly-like substance (vitreous) inside the eye becomes more liquid. Microscopic fibers within the vitreous tend to clump and cast tiny shadows on your retina, which appear to you as floaters. Eye floaters are caused for various reasons, some more serious than others.