The London Ophthalmology Centre
POSTERIOR VITREOUS DETACHMENT
What is Posterior Vitreous Detachment?
Posterior Vitreous Detachment (PVD) is a NATURAL process of the 'jelly' (vitreous) of the eye, and is present in about 75 per cent of people over the age of 65, but can occur at a much younger age, particularly if you are short sighted, and in some, for no known reason.
As people get older the vitreous jelly becomes more liquid-like and looses its attachments to the back of the eye -at the retina, the light sensitive layer.
What is the Vitreous?
The vitreous is a jelly-like substance which takes up the space behind the lens and in front of the retina. When we are born the vitreous is a solid clear jelly made up with 99 per cent water. As we age, the jelly becomes less clear and more fluid-like. These structural changes eventually lead to a PVD and the appearance of 'floaters' in your vision.
What are Floaters?
When the vitreous jelly becomes loose and mobile it is less clear than before and these opacities can be seen by our retina (the light sensitive layer) of our eye. These minute opacities, called floaters, can appear in 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. Floaters, especially in the young, can also be caused by other disorders, such as inflammation within the eye. It is advisable to seek medical advice for any new symptom.
Why may/do I see Flashing lights?
The flashing lights that may occur are also caused by the PVD. As 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 by the optic nerve). 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.
What will happen to my sight?
Posterior vitreous detachment does not in itself cause any permanent loss of vision. You may have some difficulties to begin with because of the floaters and flashing lights though these do not cause permanent sight loss. The flashing lights will eventually stop, and usually people find that the symptoms calm down after about three to six months. Most 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.
What if I am to have cataract surgery?
Some people after cataract surgery (removal of the cloudy lens inside the eye) noticed their floaters are more prominent. This is because the cloudy lens has been replaced with a new clear one that allows more light in the eye so you see more detail- including the changes in the jelly of your eye. Also any surgery inside the eye can precipitate a PVD.
What should I look out for?
In a few people (less than 5 per cent) a PVD may lead to the retina tearing, as the jelly looses its attachments to it, 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:
A sudden increase in size and number of your floaters,
a change/increase in the flashing lights,
you notice a dark "curtain" falling across your vision or a permanent blurring of vision.
If you experience any of these symptoms you should seek medical advice within 24 hours. This is particularly important as early intervention may allow treatment of a tear before it becomes a detachment, and also increase the chances of a good recovery from a retinal detachment, which has already occurred.
What treatment is available?
There is no medical treatment (drops or tablets) that reduces floaters. Surgery for a PVD is not advisable in the majority of cases, as surgery carries more risk of sight loss than the condition itself.
Laser treatment can sometimes reduce the size of floaters if they are troublesome.
If you do experience a retinal tear it may be treatable by laser of freezing the tear. Retinal detachment will require formal surgery in most cases.
Will I need to keep seeing my doctor?
Your ophthalmologist (the hospital eye specialist) will give you a thorough examination during your first visit. They will pay special attention to whether or not the retina is in any danger. If it isn't then they may not need
to see you again. However if you begin to experience the symptoms warning of a possible retinal detachment, such as increased or definite change in floaters, more severe flashing lights and/or a 'curtain' falling over your vision then an urgent trip to the eye doctor is again necessary.
V Sharma BSc FRCOphth Clinical Director