Eye conditions
What are flashes and floaters?
Floaters are small specks, lines or “cobwebs” that drift across your vision. Flashes are flickers of light when there’s no light really there. Both are very common and usually harmless.
Anyone can get them, but they’re more common as you get older, if you’re short-sighted or if you’ve had eye surgery. Most happen because the clear jelly inside your eye changes naturally with age.
Occasionally, though, new flashes or a sudden increase in floaters can be a sign of a more serious problem, such as a retinal tear or detachment, which needs treating quickly. That’s why it’s important to know the warning signs and get new symptoms checked.
Know the signs
Floaters, flashes and who gets them
Floaters
- Grey or black specks, lines or "cobwebs" in front of your eyes
- They move when your eyes move, but drift slightly behind when your eyes start or stop moving
- Easier to see against a bright background, such as a white wall or blue sky
- What you see is a shadow: bits of material in the jelly inside your eye cast shadows on the retina
Flashes
Flashes are sensations of light when no light is really there. They happen when the jelly inside your eye pulls on the retina.
- Tiny bright lights like sparklers, or flashes like lightning
- Brief: each flash usually lasts a second or so, but they often come back
- More noticeable when you move your eyes or in a dark room
Who gets them?
Anyone can get flashes and floaters, but they’re more common if you:
- Are older, as the jelly in your eye naturally changes with age
- Are short-sighted (myopic)
- Have had eye surgery, such as cataract surgery
- Have had an eye injury or inflammation inside the eye
When to get help
Warning signs
Floaters are very common and normally harmless. Occasionally, though, flashes or an increase in floaters can be a sign of something more serious, such as retinal detachment, which needs treating as soon as possible.
Book an appointment promptly if you notice:
- A sudden shower of floaters across your vision
- A new, large floater
- Floaters together with flashes of light
Go to eye casualty straight away if:
- A shadow or curtain spreads across the vision in one eye. This is the most serious warning sign.
- Nottingham QMC Eye Casualty: 0115 924 9924 (ext. 42882)
- Leicester Royal Infirmary Eye Casualty: 0116 254 1414
How it works
What's happening inside your eye
Flashes and floaters come from changes in the vitreous, the jelly that fills your eye, and how it pulls on the retina behind it.
The vitreous
A clear, jelly-like material that fills most of the inside of your eye. Bits of material floating in it cast the shadows you see as floaters.
The retina
A thin layer of nerve tissue lining the back of your eye. It turns light into signals for your brain, a bit like the film in a camera.
Vitreous detachment
As you get older, the vitreous becomes more liquid and can shrink away from the retina. Pulling on the retina causes flashes and new floaters.
These changes are more likely, and happen earlier, if you’re short-sighted. They can also follow an eye injury or inflammation inside the eye. People with high short-sightedness also have a higher risk of retinal detachment, which is one reason we offer myopia control for children. Our 3D OCT scans can show vitreous detachments in detail. See more terms in our eyecare glossary.
A different kind of flash
Flashes or migraine?
Some people with migraines see a different type of flash. Migraine flashes are usually shimmering, jagged lights that last around 15 minutes. They tend to start in the centre of your vision and slowly spread towards the edges, and may be followed by a throbbing headache, often on one side of the head.
Flashes caused by the vitreous pulling on the retina are different: they’re brief, last a second or so and keep coming back, often when you move your eyes. If you’re not sure which you’re seeing, get your eyes checked.
Your appointment
Getting flashes and floaters checked
Anyone with new flashes, or a sudden new floater or floaters, should have their eyes examined promptly. In most cases we can rule out anything serious at the appointment.
What happens at your appointment
Tell us what you've noticed
We'll ask when your flashes or floaters started, what they look like and whether they've changed.
Eye drops
We put drops in your eyes to widen your pupils, so we can see the back of your eyes clearly.
Dilated eye examination
We look closely at the vitreous and retina with specialised equipment to check for tears or detachment.
Your results
We'll explain what we've found. Usually we can rule out anything serious straight away.
Arrange a lift
The drops blur your vision for a few hours, so you won't be able to drive afterwards.
Do flashes and floaters need treatment?
Usually not. Once we’ve ruled out anything serious, flashes normally settle down on their own within a few days or weeks.
Floaters can last longer, but most people find their brain learns to ignore them after a while. If we find a retinal tear or detachment, we’ll refer you urgently for treatment.
After the eye drops
The drops used to widen your pupils have a temporary effect on your vision, which wears off within a few hours. You won’t be able to drive until it has, so arrange a lift or other transport.
In extremely rare cases, the drops can raise the pressure in your eye. Go straight to your local eye casualty if you notice:
- A red, painful eye
- Haloes around lights
- Feeling sick or stomach cramps
FAQs
Frequently asked questions about flashes and floaters
What causes floaters in the eye?
Floaters are clumps or bits of material in the vitreous, the jelly that fills the back of your eye. What you see is the shadow they cast on the retina. They become more common as the vitreous naturally changes with age, which tends to happen earlier if you’re short-sighted.
What causes flashes of light in my vision?
Flashes happen when the vitreous pulls on or tears the retina. They usually last a second or so but often come back, and may be more noticeable when you move your eyes or in a dark room.
Are flashes and floaters serious?
Usually not. Floaters are very common and normally harmless. But a sudden shower of floaters, a new large floater, or floaters with flashes can be a sign of a retinal tear or detachment, so get them checked promptly.
What is the most serious warning sign?
A shadow or curtain spreading across the vision in one eye. Go to eye casualty straight away, for example Nottingham QMC Eye Casualty (0115 924 9924, ext. 42882) or Leicester Royal Infirmary Eye Casualty (0116 254 1414).
Will floaters go away?
Floaters can last a long time, but most people stop noticing them after a while. Flashes usually settle within a few days or weeks.
Are migraine flashes the same?
No. Migraine flashes are usually shimmering, jagged lights that last around 15 minutes and spread from the centre of your vision outwards, sometimes followed by a headache. Flashes from the vitreous are brief and keep coming back.
Can I drive after having my eyes examined for flashes and floaters?
No. The drops used to widen your pupils blur your vision for a few hours, so you won’t be able to drive until the effect wears off.
Are short-sighted people more likely to get floaters?
Yes. The changes in the vitreous that cause floaters are more likely, and happen earlier, if you’re short-sighted. High short-sightedness also raises the risk of retinal detachment.
Medically reviewed by Amar-Kaash Gandecha, BSc(Hons) MCOptom DipTp(IP), Prof Cert Glauc, Director and Optometrist. Last reviewed 14 August 2026.
Noticed new flashes or floaters?
Book an appointment at your local Opticare practice and we’ll check your eyes promptly. If a shadow or curtain spreads across your vision, go to eye casualty straight away.