What are floaters?
Floaters are the little specks, flecks of "lint," or semi-transparent veils that float across one's line of vision. They typically "slosh" around when moving your gaze from side to side or up and down, but always return to the same approximate position within your field of vision a few seconds after stopping eye movement.
Floaters are the remnants of the vitreous gel that once filled the globe (eyeball). In infancy and early childhood the vitreous has a purpose: to provide a transparent medium of support for the under-developed, soft walls of the eye. But with full growth of the body, the vitreous is no longer needed. The gel begins to separate out into its component parts: a clear saline-like liquid and the fine threads of protein that once made up the matrix of the gel (this is called syneresis). As the fine threads of protein clump together they can be seen in slightly out-of-focus silhouette. But since the base of the body of vitreous gel is still adherent to the back of the iris/lens, it does not float around completely free like the white specks in a Christmas snow globe -so it cannot completely settle to the bottom of the eye as does the "snow" in the Christmas globe.
Floaters are more common in nearsighted eyes and also after cataract/lens implant surgery. They are not in themselves dangerous but should be investigated by an eye doctor if they suddenly appear. This is to rule out the (unlikely) possibility of the separating gel having pulled a tear or hole in the underlying retina.