Floaters and flashes are common, particularly as the eye ages. Most are caused by harmless changes in the clear gel inside the eye, but the same symptoms can be the first warning of a retinal tear or retinal detachment.
Arrange an urgent same-day eye assessment if floaters or flashes appear for the first time, begin suddenly, increase noticeably or occur with blurred vision, eye pain, recent eye surgery or an eye injury.
Seek immediate emergency eye care if you see a dark curtain, shadow or missing area of vision, or if your sight suddenly deteriorates. A retinal detachment is usually painless but can cause permanent sight loss if treatment is delayed.
Do not wait to see whether new symptoms settle and do not rely on an ordinary sight test booked several weeks ahead. Contact an urgent optometrist, local urgent eye-care service, NHS 111 or an eye casualty department according to services in your area.
This guide provides general information and cannot distinguish a harmless vitreous change from a retinal tear. That requires an examination of the back of the eye, usually after the pupils have been dilated.
When are floaters and flashes urgent?
New or suddenly changing symptoms need prompt assessment because a retinal tear may be treated before it progresses to a detachment.
Ask for an urgent optician appointment or contact NHS 111 if:
- you see floaters or flashes for the first time;
- they start suddenly;
- the number of floaters suddenly increases;
- flashing becomes more frequent or intense;
- you see a shower of black dots;
- your vision becomes blurred;
- part of your visual field seems missing;
- you have eye pain or marked redness;
- symptoms begin after eye surgery;
- symptoms follow an eye or head injury.
Seek immediate assessment without delay if you develop:
- a dark curtain or veil moving across your vision;
- a fixed shadow at the side, top or bottom of your visual field;
- sudden substantial loss of sight;
- rapidly worsening blurred vision with flashes or floaters;
- severe eye injury or chemical exposure;
- visual changes with weakness, facial drooping or difficulty speaking.
The NHS advises urgent assessment for first-time or sudden floaters and flashes, a sudden increase, blurred vision, pain, a curtain or shadow, and symptoms following eye surgery or injury. See the NHS guidance on floaters and flashes.
What do eye floaters look like?
Floaters are shapes that appear to drift through your vision. They are usually easiest to notice when looking at a bright, plain background such as a white wall, blue sky or computer screen.
They may look like:
- small black or grey dots;
- transparent circles;
- threads or squiggly lines;
- cobwebs;
- tadpole-like shapes;
- small flies or specks;
- a cloudy ring.
Floaters often move when your eye moves and then continue drifting after the eye stops. They may seem to move away when you try to look directly at them.
The shapes are not normally sitting on the surface of the eye. They are shadows cast onto the retina by small clumps or strands within the vitreous, the transparent gel filling most of the eyeball.
A few longstanding floaters that have not changed and do not affect vision are less concerning. A sudden group of new spots, a dense cobweb or a shower resembling pepper, soot or flies requires urgent assessment.
What do flashes of light look like?
Eye flashes are brief lights that are not actually present in the environment. They may appear as:
- white flickers;
- small sparks;
- lightning streaks;
- arcs of light;
- a camera-flash effect;
- flashing at the edge of one eye.
Flashes associated with changes in the vitreous are often brief and more noticeable in dim lighting or when the eye moves. They may occur repeatedly over days or weeks.
They happen when the vitreous pulls on or stimulates the retina. The retina sends a signal that the brain interprets as light even though no external light caused it.
Rubbing or pressing a closed eye can also produce temporary light patterns, but unexplained new flashes should not be tested repeatedly by pressing on the eye.
What is posterior vitreous detachment?
Posterior vitreous detachment, or PVD, is the most common explanation for sudden floaters and flashes in adults over approximately 50.
The vitreous is a transparent gel that fills the space between the lens and retina. With age, it becomes more liquid and shrinks. It can then separate from the retina at the back of the eye.
This separation can produce:
- a sudden prominent floater;
- a ring-shaped floater;
- cobweb-like strands;
- flashing at the edge of vision;
- several new small floaters.
PVD itself is not the same as retinal detachment. In most people it does not permanently damage vision and does not require treatment.
The difficulty is that symptoms alone cannot show whether the separating vitreous has torn the retina. Moorfields Eye Hospital explains that most PVD episodes are harmless, but approximately one in ten may involve bleeding, a retinal tear or retinal detachment.
This is why even a likely PVD should be examined when symptoms first develop. Read the Moorfields overview of PVD, flashes and floaters.
What is a retinal tear or detachment?
The retina is the thin, light-sensitive layer lining the back of the eye. It converts light into electrical signals that travel to the brain.
When the vitreous separates, it can remain firmly attached to one part of the retina. Pulling at that point may create a retinal hole or tear.
Fluid can then pass through the break and collect beneath the retina, separating it from the tissue underneath. This is a retinal detachment.
Possible warning symptoms include:
- a sudden burst or shower of floaters;
- new repeated flashes;
- a dark shadow in peripheral vision;
- a curtain moving across the eye;
- blurred, distorted or reduced sight;
- a missing section of the visual field.
A detachment usually does not make the eye red or painful. Waiting for pain can therefore lead to dangerous delay.
If the central retina, called the macula, remains attached when treatment occurs, the chance of preserving detailed central vision is generally better. Once the macula detaches, vision can remain reduced even after successful surgery.
The NHS describes retinal detachment as a condition that must be treated quickly to prevent permanent loss of sight. See its guide to retinal-detachment symptoms and treatment.
Who is at greater risk of a retinal problem?
Anyone can develop a retinal tear, but certain factors increase the likelihood that flashes and floaters represent more than an uncomplicated age-related change.
Risk factors include:
- increasing age;
- significant short-sightedness or myopia;
- previous cataract or other eye surgery;
- a recent blow to the eye or head;
- a previous retinal tear or detachment;
- a detachment in the other eye;
- a family history of retinal detachment;
- thin or weak peripheral retinal areas such as lattice degeneration;
- inflammation inside the eye;
- certain inherited eye conditions.
Short-sighted eyes are often longer from front to back, which can place greater tension on the peripheral retina. PVD may also occur at a younger age in people with substantial myopia.
Cataract surgery is very common and most patients do not develop a retinal detachment. Nevertheless, new flashes or floaters after surgery should be reported urgently.
Symptoms following an injury need assessment even when the eye looks normal externally. A retinal tear or internal bleeding may not be visible without specialist equipment.
What other conditions can cause floaters or flashes?
PVD and retinal tears are important causes, but they are not the only possibilities.
Vitreous haemorrhage
Bleeding into the vitreous may cause a shower of dark dots, cobwebs, smoke, haze or sudden loss of vision. It can occur when a retinal tear damages a blood vessel.
Other causes include diabetic retinopathy, retinal-vein problems, trauma and abnormal blood vessels. The eye can remain white and painless despite significant internal bleeding.
People with diabetes should continue attending retinal screening, but new floaters or vision loss should be assessed urgently rather than waiting for the next routine screening appointment.
Uveitis
Uveitis is inflammation inside the eye. It can cause floaters, blurred vision, eye pain, redness and sensitivity to light.
The NHS advises urgent assessment for eye pain, marked light sensitivity, flashing or blurred vision, or a very red eye. Uveitis requires treatment to control inflammation and prevent complications.
Migraine aura
Migraine aura can produce flashing, shimmering or zigzag patterns. These often expand gradually over several minutes and may affect both eyes or the same side of the visual field in each eye.
The visual effect commonly lasts between five minutes and an hour and may be followed by headache, nausea or sensitivity to light. Some people experience aura without headache.
Vitreous flashes are more often brief, lightning-like flickers at the edge of one eye. However, this distinction is not always clear enough for self-diagnosis.
New visual disturbance in one eye, persistent loss of vision or symptoms unlike your usual migraine need urgent assessment. Our guide to migraine symptoms and aura explains the typical pattern.
Inflammation, infection and injury
Inflammation, infection, foreign bodies and eye trauma can cause floaters or light phenomena alongside pain, redness or reduced vision.
These symptoms should not be attributed to an ordinary PVD without examination. See our guide to red eyes, eye pain and urgent warning signs.
How can you tell whether symptoms affect one or both eyes?
The brain combines visual information from both eyes, so it can be difficult to know where a disturbance originates.
When symptoms are present, you can briefly cover one eye and then the other without pressing on them. This may help establish whether the floater, flash or missing area remains visible through only one eye or through both.
A floater inside one eye disappears when that eye is covered. Migraine aura caused by activity in the brain is usually present in the visual field of both eyes, even when it seems stronger on one side.
This simple check can provide useful information but should not delay urgent care. A new one-eye disturbance is particularly important, and a visual problem affecting both eyes can still have serious neurological causes.
Call 999 for sudden visual disturbance accompanied by:
- facial weakness;
- arm or leg weakness;
- difficulty speaking;
- severe imbalance;
- confusion;
- a sudden exceptionally severe headache.
What happens during an urgent eye examination?
The optometrist or ophthalmology team will ask when the symptoms began, which eye is affected and whether they have changed. They will also ask about short-sightedness, surgery, injuries and previous retinal problems.
Testing may include:
- reading an eye chart;
- checking pupil reactions;
- measuring eye pressure;
- examining the front of the eye with a slit lamp;
- using dilating drops;
- examining the retina through a wide pupil;
- looking carefully at the peripheral retina;
- an ultrasound scan if blood or another opacity blocks the view.
Dilating drops can blur near vision and increase sensitivity to light for several hours. Take sunglasses and avoid driving yourself unless the service has specifically said it will be safe.
A photograph of the central retina alone may not be enough to exclude a small peripheral tear. The College of Optometrists advises a dilated fundal examination using an appropriate indirect viewing technique when a retinal break is suspected.
If no tear is found, you may be discharged with instructions about warning symptoms. Occasionally a repeat examination is arranged because a tear can become visible later as the vitreous separation progresses.
How are retinal tears and detachments treated?
An uncomplicated PVD does not usually need treatment. Flashes commonly reduce as the vitreous finishes separating, while floaters may persist but become less noticeable as the brain adapts.
Retinal tear treatment
A symptomatic tear can often be sealed before a detachment develops. Treatment may use:
- laser photocoagulation, which creates small burns around the tear that form a securing scar;
- cryotherapy, which freezes the outside wall of the eye around the tear to produce a similar seal.
Treatment reduces the risk of detachment but does not remove existing vitreous floaters. You still need to watch for new shadows, increased floaters or worsening vision afterwards.
Retinal-detachment surgery
A detached retina normally requires surgery. The procedure depends on the location and extent of the detachment and may include:
- vitrectomy, removing vitreous gel and replacing it with gas or oil;
- a scleral buckle placed around the outside of the eye;
- pneumatic retinopexy using a gas bubble in selected cases;
- laser or freezing treatment around retinal breaks.
A gas bubble may require particular head positioning and temporarily prevents flying or travel to high altitude. Nitrous oxide anaesthetic can be dangerous while an intraocular gas bubble remains, so other healthcare professionals must be told.
Surgery commonly prevents further deterioration, but the amount of vision recovered depends on factors including how much retina detached and whether the macula was involved.
Do ordinary floaters need treatment?
Most longstanding floaters do not need treatment. They often become less intrusive over time, even if they do not physically disappear.
Practical strategies include:
- moving the eyes gently rather than chasing a floater;
- reducing screen glare;
- using appropriate lighting;
- wearing sunglasses in bright conditions;
- allowing time for the brain to adapt.
There are procedures for severe persistent floaters, but they are not routine solutions for every person.
Vitrectomy
Vitrectomy removes the vitreous gel and can substantially reduce floaters. It is eye surgery and carries risks including cataract, retinal tear, retinal detachment, infection, bleeding and vision loss.
Laser vitreolysis
Laser treatment attempts to break larger floaters into smaller pieces. Suitability is limited, evidence is mixed and the laser itself can damage structures inside the eye if not used appropriately.
A careful discussion is needed when floaters are genuinely disabling. Do not choose an invasive treatment until a retinal specialist has confirmed the diagnosis and explained the balance of benefit and risk.
Supplements, eye exercises and drops do not remove floaters located within the vitreous. Be wary of products promising to dissolve them without credible clinical evidence.
When should previously checked symptoms be reassessed?
A normal initial examination is reassuring, but it does not mean you should ignore later changes.
Seek another urgent assessment if you develop:
- a sudden increase in floaters;
- a new shower of black dots;
- more frequent flashes;
- a new blind spot or shadow;
- a curtain effect;
- new blurred or reduced vision;
- symptoms in the other eye.
Do not assume that these are merely a continuation of the PVD already examined. A retinal tear can occasionally develop after the first assessment.
Attend any recommended follow-up even if symptoms seem less noticeable. If you are uncertain whether a change is important, contact the eye service that examined you or use NHS 111.
Frequently asked questions
Are eye floaters normal?
A few stable floaters that have been present for a long time are common. New, sudden or increasing floaters need urgent assessment to exclude a retinal tear.
What does a dangerous floater look like?
No shape is diagnostic by itself. A sudden dense cobweb, shower of dots, smoky haze or many new floaters is particularly concerning, especially with flashes or blurred vision.
Are flashes always caused by retinal detachment?
No. PVD commonly causes flashes without a retinal detachment. The same symptom can occur with a retinal tear, so an eye examination is needed.
Can a retinal detachment happen without pain?
Yes. Retinal detachment is typically painless. Warning signs are visual, including floaters, flashes, shadows, a curtain effect and blurred or missing vision.
How quickly should new flashes and floaters be checked?
Seek urgent advice the same day. Contact an urgent optometrist, local urgent eye-care service, NHS 111 or eye casualty according to local arrangements.
Should I go to A&E for floaters?
New floaters need urgent triage. A dark curtain, missing vision or sudden sight loss requires emergency eye care without delay. NHS 111 can direct you when the local pathway is unclear.
Can an optician diagnose a retinal tear?
An appropriately equipped and trained optometrist can perform a dilated retinal examination and refer urgently when a tear or detachment is suspected. Some patients are sent directly to an ophthalmologist or eye casualty.
Can a standard eye test detect a retinal detachment?
A retinal examination can detect a detachment, but a routine sight test or central retinal photograph may not adequately examine the far peripheral retina. Tell the practice about sudden symptoms when booking.
Can stress cause eye floaters?
Stress may increase awareness of existing floaters but does not safely explain a sudden new group. New or changing symptoms still need examination.
Can dehydration cause floaters?
Dehydration is not a reliable explanation for sudden floaters. Do not delay an eye check by trying to correct hydration first.
Do floaters go away after PVD?
They may remain but often become less noticeable over weeks or months. Flashes usually decrease as the vitreous stops pulling on the retina.
Can migraine cause flashing lights?
Yes. Migraine aura commonly creates expanding zigzags, shimmering or patterned light affecting both visual fields for several minutes. New, one-eye or persistent visual symptoms require assessment.
Can diabetes cause floaters?
Diabetic retinopathy can cause bleeding into the vitreous, producing spots, haze or sudden loss of vision. New symptoms require urgent assessment even if routine diabetic eye screening is up to date.
Can cataract surgery cause floaters?
Floaters may become more noticeable after cataract surgery, and surgery is also a retinal-detachment risk factor. New flashes or floaters after an operation should be reported urgently.
Can I drive with dilated pupils?
Dilating drops can cause blurred near vision and light sensitivity. Arrange alternative transport and do not drive until your vision has returned to a level that is safe and legal.
Can rubbing the eyes cause retinal detachment?
Ordinary gentle rubbing is not a usual cause, but significant trauma can damage the retina. Avoid pressing hard on the eye, especially when symptoms are unexplained.
