This a common degenerative change which occurs in one or both eyes of most people after middle age. It is not usually caused by trauma of any kind. Everybody has jelly like fluid filling the posterior cavity of both eyes. This is called the vitreous humour. In a PVD this jelly has shrunken and dislodged forwards in the eye. As the jelly pulls off it stimulates the retina and causes flashes to be seen.
The retina lines the back of the eye like a tiny curved cinema screen and collects visual images to send to the brain. Thickenings in the jelly cast shadows on the retina and are seen as floating shapes, or a cobweb in the vision.
What happens next?
A PVD is harmless. The flashes stop with time and usually the occasional floater remains. Floaters become less obvious as the months go by. Very occasionally the jelly pulls a hole in the retina. This is more serious and can cause bleeding or a retinal detachment. Retinal detachments are treated urgently to prevent visual loss. Bleeding usually stops on its own and eventually clears with time.
How do I recognise a retinal detachment?
If you have a retinal detachment you may notice:
- Increased floaters
- Increased flashing lights
- Black persistent shadows at the edges of vision in one eye
- The impression of a rising or falling curtain
- Sudden drops in vision within 24 hours
If any of the above occur you are advised to seek further advice urgently.