A clear jelly, the vitreous or 'vitreous', fills the middle of the eye. The vitreous lies against the retina in the normal eye. It is transparent like glass, so light passes through it to reach the retina: the retina is the film that lines the back of the eye.
The eye is like a small ball, the size of a table-tennis ball. Light enters the eye, and then passes through to fall on the retina. The retina turns the light into electrical signals, which are then sent to the brain.
As you get older the vitreous may shrink away from the retina. This may happen earlier if you are short sighted or have injured your eye. A PVD probably occurs in all of us.
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 shrinkage is essentially like a jelly liquefying, and no harm comes to the eye.
The vitreous may shrink in different ways. This is described on the PVD page.
the vitreous detaches causing floaters and a few flashes
Floaters are naturally much more noticeable if you only have one good eye (and this process is happening in the good eye).
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. Most people adjust to the floaters...the brain learns to accept them and ignore them over time, and they may break up a little over time, and after a few months very few people are very bothered by them.
However, patients with only one eye do notice them much more easily.
If the floaters are very troublesome indeed, a few departments off laser treatment. The floater is targeted by a very bright light that disperses the floater. Yag laser vitreolysis.
If the doctor checks your eye and all is well, the floaters and flashes subside. However, you usually need a further examination if
- you suddenly develop a lot more flashes or floaters (this could be a small tear)
- a shutter or curtain of blurred vision drifts across your eye, sometimes from below. To check for this, cover one eye at a time for a few seconds every day. If the eye you have not covered sees well in all directions, all is well.
- 15% of people with a PVD and symptoms (flashes/floaters) do have a retinal tear. If the flashes do not settle after a few days and occur during the day a tear is more likely.
An area of poor sight drifting across your vision:
if such a problem develops, you need a check the same day or next
morning to determine whether or not there is a retinal detachment.
Test your sight everyday covering one eye at a