Suddenly noticing new floaters or brief flashes of light can be frightening, particularly if you have never experienced them before.
One of the most common causes is posterior vitreous detachment, usually shortened to PVD.
PVD happens when the clear jelly-like substance filling the centre of the eye — the vitreous — gradually changes with age and separates from the retina at the back of the eye.
In most people, this is a normal age-related process rather than a disease. It usually does not cause permanent loss of vision and often requires no treatment.
However, there is an important reason new symptoms should not simply be ignored: as the vitreous separates, it can sometimes pull hard enough on the retina to create a retinal tear. A tear can then develop into a retinal detachment, which can permanently damage sight if it is not treated promptly.
For this reason, new flashes or a sudden increase in floaters should be assessed urgently, even though most people ultimately turn out to have an uncomplicated PVD.
This guide explains what posterior vitreous detachment is, what it feels like, why floaters and flashes occur, when retinal damage is possible and what happens during an eye examination.
What Is Posterior Vitreous Detachment?
The inside of the eye is filled with a transparent gel called the vitreous humour.
When you are younger, this gel is relatively firm and attached to the retina — the light-sensitive layer lining the back of the eye.
As you get older, the vitreous gradually becomes more liquid.
It begins to shrink and pull away from the retina.
Eventually, the back surface of the vitreous separates from the retina. This is posterior vitreous detachment.
The word “detachment” sounds alarming, but PVD itself is very different from a retinal detachment.
In an uncomplicated PVD:
- the vitreous moves away from the retina;
- the retina itself stays in place;
- central vision is usually unaffected;
- no surgery is normally needed.
RNIB describes PVD as a natural change in the vitreous that becomes increasingly common with age.
What Are the Symptoms of PVD?
The most characteristic symptoms are new floaters and flashes of light.
Floaters
Floaters can look like:
- small black dots;
- grey specks;
- threads;
- squiggly lines;
- rings;
- cobwebs;
- a larger circular or curved floater.
They appear to drift as your eyes move.
They are often easiest to notice when looking at a bright, plain background such as a white wall, computer screen or blue sky.
Floaters are actually shadows cast onto the retina by small structures within the vitreous.
Flashes
Flashes may appear as:
- brief streaks of light;
- small sparks;
- flickering at the edge of vision;
- lightning-like flashes in peripheral vision.
They can be particularly noticeable in darkness.
Flashes occur because the separating vitreous pulls on the retina and mechanically stimulates retinal cells.
Our guide to eye floaters and flashes explains these symptoms and their other possible causes in more detail.
Why Does PVD Happen?
The main cause is ageing.
Over time, the vitreous changes from a firm gel into a more liquid consistency.
Microscopic collagen fibres inside it clump together, creating the shadows we perceive as floaters.
At the same time, the vitreous shrinks and gradually separates from the retinal surface.
PVD becomes much more common from middle age onwards.
It can happen earlier in people with certain risk factors.
These include:
- significant short-sightedness;
- previous cataract or other eye surgery;
- eye injury;
- inflammation inside the eye.
Having PVD in one eye also makes it reasonably likely that the other eye will eventually undergo the same age-related process, although not necessarily at the same time.
People who have undergone cataract surgery may therefore be particularly familiar with being warned about new flashes or floaters. Our guide to cataracts and cataract surgery explains that treatment in more detail.
Is Posterior Vitreous Detachment Dangerous?
Most PVDs are not dangerous.
The vitreous separates without significantly damaging the retina, and symptoms gradually become less intrusive.
The concern is what happens while the vitreous is pulling away.
In some places it may be firmly attached to the retina.
As it separates, it can pull hard enough to create a retinal tear.
RNIB estimates that around 10% to 15% of people with PVD develop a retinal tear.
A retinal tear is important because fluid can pass through the opening and collect underneath the retina.
This can cause the retina to lift away from the back of the eye — a retinal detachment.
The risk of a tear is highest around the time PVD symptoms first appear and during the following weeks.
That is why the first examination matters even when you can still see normally.
When Should Flashes and Floaters Be Checked Urgently?
The NHS advises urgent assessment if you:
- develop floaters for the first time;
- suddenly develop flashes of light;
- notice a sudden increase in existing floaters or flashes;
- develop blurred vision alongside them;
- develop symptoms after eye surgery or injury;
- see a dark curtain or shadow moving across your vision.
RNIB advises having new PVD-type symptoms examined by an optometrist or ophthalmologist within 24 hours.
A particularly important warning sign is a sudden shower of many small floaters. This can sometimes represent bleeding into the vitreous associated with a retinal tear.
A dark curtain, shadow or missing section of peripheral vision is even more concerning because it can indicate that retinal detachment has already begun.
If you cannot obtain an urgent optometry or eye-clinic assessment, NHS 111 can advise where to seek help locally.
PVD vs Retinal Detachment: What Is the Difference?
The names sound similar, but they describe very different events.
| Posterior vitreous detachment | Retinal detachment |
|---|---|
| The vitreous gel separates from the retina | The retina itself separates from the back wall of the eye |
| Very common with ageing | Much less common |
| Usually does not damage vision | Can permanently damage vision |
| Usually requires no treatment | Usually requires urgent treatment |
| Can cause floaters and flashes | Can also cause floaters and flashes plus shadow or loss of vision |
The problem is that the early symptoms overlap.
You cannot reliably determine at home whether new flashes and floaters represent an uncomplicated PVD, a retinal tear or the beginning of a retinal detachment.
That requires examination of the retina.
Our guide to retinal detachment warning signs and treatment explains what happens if the retina itself begins to separate.
How Is Posterior Vitreous Detachment Diagnosed?
An eye professional needs to examine the retina.
You will usually be given eye drops that widen — or dilate — the pupils.
This allows an optometrist or ophthalmologist to examine the peripheral retina, where small tears can otherwise be difficult to see.
The examination is painless, although the bright light can be uncomfortable.
The dilating drops can leave your vision blurry and sensitive to light for several hours.
You may therefore be advised not to drive home afterwards.
The clinician will look for:
- evidence that PVD has occurred;
- a retinal tear;
- retinal detachment;
- bleeding inside the eye;
- other causes of the symptoms.
If the view of the retina is difficult, an ultrasound scan of the eye may occasionally be used.
If the retina looks healthy, you may simply be given advice about symptoms to watch for.
Does Posterior Vitreous Detachment Need Treatment?
Usually, no.
There is normally nothing that needs to be done to reattach the vitreous.
The eye continues to function perfectly well once the vitreous has separated.
Flashes commonly become less frequent as the vitreous stops pulling on the retina.
Floaters can persist for longer.
They may not physically disappear completely, but the brain gradually becomes better at ignoring them and they often become much less noticeable.
RNIB notes that the PVD process can continue for several weeks or months before symptoms settle.
Treatment is only usually needed when there is a complication such as a retinal tear or detachment.
What if a retinal tear is found?
A retinal tear can often be sealed using laser treatment or freezing treatment called cryotherapy.
The aim is to create a strong scar around the tear so that fluid cannot pass through and lift the retina away.
Treating a tear before retinal detachment develops is generally much simpler than treating a detached retina.
Can You Exercise With PVD?
Most people with uncomplicated PVD can continue normal everyday activities.
RNIB states that there is no evidence that ordinary activities cause complications in most people with PVD.
However, some ophthalmologists recommend avoiding particularly strenuous or high-impact activity during the early weeks when the vitreous is still actively separating, especially if there are additional retinal risk factors.
This might include activities involving:
- very heavy lifting;
- high-impact exercise;
- contact sports;
- activities with a significant risk of eye or head trauma.
Advice varies according to the individual eye examination.
If your ophthalmologist gives you specific activity restrictions, follow those rather than generic online advice.
Normal activities such as reading, watching television, computer work and walking do not usually cause PVD to worsen.
What Happens After the Initial Examination?
If your retina is normal and uncomplicated PVD is diagnosed, you may not need ongoing hospital treatment.
What matters is knowing what changes should bring you back urgently.
Seek another urgent assessment if you develop:
- a sudden increase in floaters;
- new or worsening flashes;
- a shower of tiny black dots;
- new blurred vision;
- a dark curtain or shadow;
- loss of part of your visual field.
Do this even if your retina was completely normal at the first examination.
A tear can occasionally develop later while the PVD process continues.
RNIB says the greatest risk of a PVD-related retinal tear is during the initial period and roughly the first six weeks.
Once the vitreous has fully separated, the risk caused by that active pulling process falls.
Frequently Asked Questions
Is posterior vitreous detachment serious?
PVD itself is usually not serious and generally does not cause permanent loss of vision. The reason it requires prompt assessment is that a minority of people develop a retinal tear.
Is PVD the same as retinal detachment?
No. With PVD, the vitreous gel separates from the retina while the retina stays attached to the eye. With retinal detachment, the retina itself lifts away from the back of the eye and requires urgent treatment.
What does a PVD floater look like?
It may appear as dots, strings, cobwebs or a larger ring-like floater. Some people notice one particularly prominent curved or circular floater when the vitreous separates from around the optic nerve.
What do PVD flashes look like?
They are often brief streaks or sparks of white light at the edge of vision. They may be more noticeable in dim light or when moving the eyes.
Does PVD hurt?
No. Posterior vitreous detachment itself is usually painless. Eye pain alongside new floaters or flashes is another reason to seek urgent assessment because other eye conditions can cause similar visual symptoms.
Can PVD cause blindness?
Uncomplicated PVD does not normally cause blindness. A retinal tear or retinal detachment occurring as a complication can threaten vision if it is not treated promptly.
How common is a retinal tear after PVD?
RNIB estimates that approximately 10% to 15% of people with PVD develop a retinal tear. Most people therefore do not develop this complication.
How long do flashes last after PVD?
They often reduce over days or weeks as the vitreous stops pulling on the retina, although the overall separation process can continue for weeks to months.
Do floaters disappear after PVD?
They may not disappear completely, but they often become less obvious with time as they move away from the central visual axis and your brain learns to ignore them.
Can PVD happen in both eyes?
Yes. It may develop in the second eye months or years after the first, although the timing varies considerably.
Can cataract surgery cause PVD?
PVD is more common after eye surgery including cataract surgery. This is one reason patients are advised to report new flashes, floaters or shadows promptly after surgery.
Does PVD need surgery?
Usually not. Surgery is not normally required for uncomplicated PVD. Treatment is directed at complications such as retinal tears or retinal detachment.
Can I drive with PVD?
If your vision remains good, PVD itself does not automatically prevent driving. However, you should not drive if your vision is significantly blurred or obscured. Also remember that dilating drops used during an eye examination can temporarily blur vision and make driving unsafe.
Should I go to A&E for new floaters?
New or suddenly increased floaters and flashes need urgent eye assessment. Depending on local services, this may be through an urgent optometrist appointment, an eye casualty department, A&E or NHS 111 guidance.
What is the most important warning sign after PVD?
A dark curtain or shadow entering your vision, loss of part of your visual field, sudden blurred vision or a major increase in floaters or flashes should be treated as urgent because these can indicate a retinal tear or detachment.
This guide provides general information and cannot distinguish uncomplicated PVD from a retinal tear or retinal detachment. New flashes or a sudden increase in floaters should be assessed urgently rather than diagnosed at home.
