What is a posterior vitreous detachment (PVD)?

Posterior vitreous detachment (PVD) is a change in your eye which does not normally cause sight loss. It is very common and most of us will develop it at some point in our lives. Although it can cause some frustrating symptoms, it does not cause pain, harm the eye, or change the way the eye works. In the vast majority of cases, PVD will not lead to long term changes in your vision. The eye is filled with a clear jelly-like substance called the vitreous gel. Light passes through the vitreous gel to focus on the retina. When the vitreous jelly comes away from the retina this is called a vitreous detachment. As you get older the various structures that make up your eye change; this includes the vitreous gel. The vitreous is made up mainly of water and collagen and it has a stiff, jelly-like consistency. As you age the vitreous becomes more watery, less jelly-like and isn’t able to keep its usual shape. As a result, it begins to move away from the retina at the back of the eye towards the centre of the eye. A PVD is a natural change that occurs in the eye. Over 75% of people aged over 65 develop a PVD, and it is not uncommon for it to develop in someone’s 40s or 50s. PVD is not a sign of a disease or eye health problem. For most of us a PVD happens naturally as we get older. PVD can cause symptoms such as floaters, little flashes of light, or a cobweb effect across your vision. Some people get all three symptoms and others may only get one or two. Some people get a lot of each of these symptoms and others hardly any. Importantly, these same symptoms can be an indication of a more serious problem, such as a retinal tear or retinal detachment, which needs urgent attention. You will not be able to tell the difference between floaters and flashes caused by PVD or retinal detachment. The only way you can tell is to have your eyes examined by an ophthalmologist or optometrist. If you suddenly experience any of the following symptoms, make sure you have your eyes examined as soon as possible – preferably on the same day or within 24 hours:
  • A sudden appearance of floaters or an increase in their size and number.
  • Flashes of light and/or a change/increase in the flashing lights you experience.
  • Blurring of vision.
  • A dark “curtain” moving up, down or across your vision, as this may mean that the retina has already partially detached.
It is important to remember that in most cases these symptoms are caused by vitreous detachment and this rarely causes any long-term problems with your vision. However, because there is a small risk that these symptoms may be a sign of a retinal tear or retinal detachment it is always best to have your eyes examined. You may find the symptoms of your PVD only last for a few weeks, but more commonly they last around six months, with the floaters and flashes of light gradually calming down over this period. For some people the floaters caused by the PVD can last for up to a year, or longer, although this is more unusual.