FLASHES AND FLOATERS
Floaters are suspended in the vitreous humour, the thick fluid or gel that fills the eye. Thus, they generally follow the rapid motions of the eye, while drifting slowly within the fluid. Floaters located slightly to the side of one's direction of gaze can be particularly annoying. When they are first noticed, the natural reaction is to attempt to look directly at them. However, attempting to shift one's gaze toward them can be difficult since floaters follow the motion of the eye, remaining to the side of the direction of gaze. Floaters are, in fact, visible only because they do not remain perfectly fixed within the eye. Although the blood vessels of the eye also obstruct light, they are invisible under normal circumstances (and thus not annoying) because they are fixed in location relative to the retina, and the brain "tunes out" stabilized images (see neural adaptation). This does not occur with floaters and they remain visible, and, in some cases when large and numerous, very annoying.
Floaters are particularly noticeable when lying on one's back and gazing at blue sky. Despite the name "floaters", many of these specks have a tendency to sink toward the bottom of the eyeball, in whichever way the eyeball is oriented; the supine position tends to concentrate them near the fovea, which is the center of gaze, while the textureless and evenly lit sky forms an ideal background against which to view them.
Floaters are not uncommon, and do not cause problems for most sufferers. However, floaters are more than a nuisance and a distraction to those with severe cases, especially if the spots seem to constantly drift through the field of vision. The shapes are shadows projected onto the retina by tiny structures of protein or other cell debris discarded over the years and trapped in the vitreous humour. It should also be noted that they can even be seen when the eyes are closed on especially bright days, when sufficient light penetrates the eyelids to cast the shadows. It is not, however, only elderly people who suffer from floaters; they can certainly become a problem to younger people, especially if they are myopic. They are also common after cataract operations or after trauma. In some cases, floaters are congenital.
Though floaters are not known to cause any type of physical obstruction, they are noted by sufferers to be a very "tough psychological barrier to overcome". Floaters have been known to catch and refract light in ways that somewhat blur vision temporarily until the floater moves to a different area. Many times they trick the sufferer into thinking they see something out of the corner of their eye that really isn't there and can start to become a very troublesome nuisance. Most sufferers are able to, with time, learn to ignore their floaters. Sadly, for people with severe floaters it is nearly impossible to completely ignore the large masses that constantly stay within almost direct view. Some sufferers have noted an increased inability to concentrate while reading, watching television, walking outdoors, and driving. For a few percentage of floater sufferers, depression can infiltrate their mindset due to the feelings of never being able to fully enjoy life without some sort of "obstruction" in their way at all times.
Normally, there is no treatment indicated. Vitrectomy may be successful in treating more severe cases, however, the procedure is typically not warranted in those with lesser symptoms due to the potential for complications as severe as blindness. Floaters may become less annoying as sufferers grow accustomed to them, even to the extent that they may no longer notice them.
Another treatment is laser vitreolysis. In this procedure a YAG laser is focused onto the floater and in a quick burst vaporizes the structure into, presumably, a less dense and not as noticeable consistency. This procedure can be time consuming and there is no consensus as to how completely effective it is. One study found laser vitreolysis "to be a safe but only moderately effective primary treatment conferring clinical benefit in one third of patients".