The vitreous is a clear jelly that fills the middle of the eye. In a normal eye the vitreous lies against the retina. It is transparent like glass, so light passes through it to reach the retina. The retina then turns the light into electrical signals, which are then sent to the brain.
As we get older the vitreous may shrink away from the retina. This may happen earlier if you are short sighted or have injured your eye.
This shrinking process may happen rather suddenly, that is over a few days. This process is called a posterior vitreous detachment.
The eye still sees well with a shrunken vitreous.The vitreous can shrink in different ways.
First, it may shrink away from the retina, and leave the retina unaffected. You may not notice if this happens.
Secondly, it may tug the retina gently. This may cause tiny flashes of light. These usually subside over a couple of weeks.
Third, you may develop floaters. Tiny amounts of pigment may come off the retina, into the vitreous, and this may cause floaters. You may see these as a spiders web or veil over the eye. The floaters disappear a little, and become less noticeable, over the next few weeks or months.
Floaters are naturally much more noticeable if you only have one good eye (and this process is happening in the good eye).
Less commonly, the vitreous may pull the retina and make a small retinal tear, or even less commonly, a detached
When the vitreous shrinks it may cause blackish floaters and flashes of light.
Occasionally the PVD (the shrinking vitreous) pulls the retina to make a retinal tear.
Or a detached retina
There is no treatment that will put the vitreous back in position. The floaters and veil that may have drifted across your sight subside by themselves. You may notice a large floater for a long time, which is a nuisance; the doctor can not remove this. As mentioned, most people become accustomed to the floater or floaters, and with a little effort ignore them.