What is a posterior vitreous detachment?
The vitreous is a clear gel-like substance that fills the back part of the inside of the eyeball. It is attached to the retina until, with time, it starts to degenerate as part of the ageing process. A posterior vitreous detachment, or PVD, occurs when the vitreous gel separates and peels away from the retina. It is common and occurs in the eye with age. In short sighted (or myopic) people, because the eyeball is slightly longer, this change takes place at a younger age (as early as your forties or fifties, instead of seventies and eighties).
Normal vitreous gel is clear and attached to the retina
Initially, the gel becomes more liquid, and the solid parts of the gel float freely in the eyeball – this can cause symptoms of new floaters. As the vitreous gel separates from the retina, you may notice flashing lights. These are usually noticed as brief sparks at the edge of your vision, particularly in dim lighting conditions, and often on eye movement. Your eyesight is otherwise normal.
Posterior vitreous detachment with strands and clumps floating in the eye
What complications could occur?
In the vast majority of cases a posterior vitreous detachment is harmless and represents the normal, natural (although occasionally annoying) aging change of the eye. If you have noticed floaters they should become much less obvious with time as the brain adjusts and eventually filters them out.
In most people, the vitreous separation from the eye occurs without the retina being affected. Sometimes, during the development of a posterior vitreous detachment, the vitreous gel can be stuck to a patch of retina and cause a tear in the retina as the gel pulls away. If the seal of the retina against the back of the eye is broken, fluid can start to track in through the tear, behind the retina, causing it to detach from the back of the eye a little like wallpaper peeling off a wall. This uncommon event occurs in approximately 1 in 10,000 of the population in general. Usually, if a tear develops in the retina people experience a very marked shower of floaters associated with flashes of light in their peripheral vision. The light is usually persistent and may occur in daylight, although most people notice it in dim lighting. Some people notice a curtain effect coming in from their peripheral visual field. This requires urgent attention by an eye doctor.
From your point of view, unfortunately, you can’t tell whether the flashing lights and floaters you notice are just due to a posterior vitreous detachment, or whether there is also a retinal tear – this can be identified by an examination of the retina.
You should remain vigilant for significant changes which may indicate a retinal tear or detachment such as
- a shower of floaters
- new, larger floaters
- blurred or hazy vision
- flashing lights which persist
- a curtain or shadow coming over part of your vision
- any loss of vision
There is usually no treatment necessary for a posterior vitreous detachment if the retina is not affected. You may always have some floaters that you didn’t before, but you will probably get used to them, and not notice them most of the time. Some of the solid bits in the vitreous gel can be quite large and dense and if you find that the floaters are really troublesome, interfering with your ability to see clearly enough, you may wish to consider vitrectomy surgery to remove the vitreous gel and floaters.