The vitreous is a clear jelly-like substance within the eye that takes up the space behind the lens and in front of the retina, the light sensitive layer at the back of the eye. It is 99% water. The other 1% consists of substances which are important in maintaining the shape of the vitreous. It is attached at the back to the retina, the layer of tissue that converts light to an image seen by the brain.
In middle age that gel becomes more fluid in texture and begins to shrink in size. The firm jelly-like central part of the vitreous becomes more liquid and the outer part (cortex) pulls away from the retina. Sometimes the vitreous breaks itâ€™s connections to the retina away and comes away from the back of the eye (detaches).
Many people are not aware that they have developed Posterior Vitreous Detachment (PVD) but some notice symptoms such as floaters or flashing lights. Floaters can take many forms from little dots, circles, lines, to clouds or cobwebs. Sometimes people experience one large floater, which can be distracting and make things difficult to read.
The flashing lights that occur are also caused by the PVD. As the outer part of the vitreous detaches from the retina it can pull on this light sensitive membrane, especially where the vitreous is attached quite strongly to the retina. The pull of the vitreous in these areas stimulates the retina. This stimulation causes the sensation of flashing lights since the brain interprets all stimulation signals from the retina as light.
95% of PVDs have no complications but for 3 months after such an episode there is an increased risk of a retinal tear forming which can lead to a retinal detachment. In 5% of cases there are signs of a retinal tear and urgent referral to the Eye Pavilion is the route to treatment.
Sometimes the vitreous is so firmly attached to the surface of the retina that as the jelly collapses it pulls quite strongly on the retina. In a few people this may lead to the retina tearing which in turn could lead to a loss of vision because of a retinal detachment.
Warning signs of a retinal tear or detachment could be an increase in size and number of your floaters, a change/increase in the flashing lights you experience. If you experience any of these symptoms you should seek medical advice within 24 hours. This is particularly important if you notice a dark â€˜curtainâ€™ falling across your vision. Early intervention may allow treatment of a tear before it becomes a detachment and increase the chances of a good recovery from a retinal detachment that has already occurred.
Will I lose any sight after a PVD?
Posterior Vitreous Detachment does not in itself cause any permanent loss of vision. Your visual acuity should remain the same, that is, you will be able to see just as you could before the Posterior Vitreous Detachment started. You may have some difficulties to begin with because of the floaters and flashing lights though these do not cause permanent sight loss.
The only threat to vision is the small chance of a retinal tear leading to a retinal detachment. It is important to stress that retinal tears and detachments are much rarer conditions and that very few people with PVD go on to develop either of these problems.
Can anything be done to help with the PVD?
Unfortunately at the moment nothing can be done medically for this condition and people do eventually get used to living with the floaters. The brain tends to adapt to the floaters and eventually is able to ignore them, so they then only become a problem in very bright light.
It is important to remember that PVD has been estimated to have occurred in over 75% of the population over 65, that PVD is essentially a harmless condition although with some disturbing symptoms and that it does not normally threaten sight.
You will appreciate that the symptoms of these two conditions are so similar we have to investigate all such instances thoroughly as a matter of some urgency and dilation of the pupils is an essential part of that examination so it takes about 30 minutes to have everything done properly.
Whilst in the great majority of cases, such symptoms indicate nothing other than a normal physiological age related change, they should be taken seriously and you should seek our advice. If you experience an increase of floaters or flashing lights or a â€˜curtainâ€™ coming over your vision, you should contact us immediately for investigation