The small spots occasionally seen in your field of vision are called floaters, or eye floaters. They may look like dots, threads, cobwebs, bubbles or dark specks drifting across your sight.
Floaters are usually caused by tiny clumps of protein, collagen or other cell debris suspended in the vitreous, the clear gel that fills much of the inside of the eye. Light passing through these irregularities creates shadows on the retina, so the spots appear to move as the eyes move. They are especially noticeable against bright, plain backgrounds such as a blue sky or a white wall.
Most floaters are harmless and become more common as the vitreous changes with age. The medical term for the perception is myodesopsia, and the Latin phrase muscae volitantes means “flying flies.” A sudden shower of new floaters, especially with flashes of light, a curtain-like shadow or vision loss, can signal a retinal tear or detachment and requires urgent eye care. Floaters should not be confused with visual snow, which is a different visual disturbance.