Author: Dr Val Phua
Estimated reading time: 13–15 minutes
What Are Flashes of Light in Vision?
Flashes of light are visual sensations that occur without a corresponding light source in the outside world.
The medical term is photopsia.
People may describe flashes as:
- Lightning streaks
- Camera flashes
- Flickering lights
- Sparks
- Stars
- Bright arcs
- Shimmering lines
- Zigzag patterns
- Coloured lights
- A glowing or flashing edge
- Brief white flashes in the side vision
Flashes are a symptom rather than a diagnosis.
They may result from:
- Age-related vitreous separation
- Retinal traction
- A retinal tear
- Retinal detachment
- Migraine aura
- Eye trauma
- Inflammation
- Bleeding inside the eye
- Retinal or neurological disease
Many flashes are caused by an uncomplicated posterior vitreous detachment, but new flashes cannot be assumed to be harmless until the retina has been examined.
How Do We Normally See Light?
Light normally enters through the cornea and pupil before being focused onto the retina.
The retina converts light into electrical signals. These signals travel through the optic nerve and visual pathways to the brain, where they are interpreted as vision.
A flash can occur without external light when the retina or visual pathways are stimulated in another way.
For example:
- Vitreous gel pulling on the retina may mechanically stimulate retinal cells.
- Migraine activity in the brain may produce shimmering or geometric visual patterns.
- Pressure on the eye may briefly stimulate the retina.
- Retinal, optic-nerve or neurological disease may create abnormal visual signals.
The visual system interprets this stimulation as light even though no light actually entered the eye.
What Do Retinal Flashes Usually Look Like?
Flashes caused by vitreous traction are commonly described as:
- A brief white arc
- A lightning streak
- A spark at the side of the vision
- A camera flash
- A curved flash near the edge of the visual field
They are often:
- Brief
- Intermittent
- More noticeable in dim lighting
- Located in the peripheral vision
- Triggered or noticed during eye or head movement
- Present in one eye
The flash may last only a fraction of a second but recur several times.
The exact appearance cannot determine whether the retina has merely been tugged or has developed a tear. A dilated retinal examination is needed.
What Is the Most Common Eye-Related Cause?
The most common ocular cause of new flashes in adults is posterior vitreous detachment, or PVD.
The vitreous is the transparent gel filling the main cavity of the eye. It contains fine fibres attached to the retina.
As the vitreous ages:
- Parts of the gel become more liquid.
- The collagen framework contracts.
- The back surface of the vitreous pulls away from the retina.
- Traction on the retina produces flashes.
- Vitreous strands cast shadows that appear as floaters.
PVD usually occurs after age 50 and becomes increasingly common with age. It may develop earlier in people with myopia, previous eye surgery, trauma or intraocular inflammation.
Is Posterior Vitreous Detachment Dangerous?
Most PVDs do not cause permanent visual damage and require no treatment.
However, the vitreous may remain firmly attached to certain retinal areas. As it separates, the traction can:
- Tear the retina
- Cause bleeding into the vitreous
- Lead to retinal detachment
- Occasionally contribute to a macular hole or macular pucker
The symptoms of uncomplicated PVD and a retinal tear can be very similar. The only reliable way to distinguish them is through a dilated retinal examination.
How Often Is a Retinal Tear Found with New PVD Symptoms?
A large prospective study found a retinal tear or rhegmatogenous retinal detachment in approximately 9.9% of eyes presenting with symptomatic PVD.
The exact rate varies between populations and referral settings, but this means that a clinically important minority of patients with new flashes and floaters have a retinal break requiring treatment.
A Weiss ring or obvious PVD does not prove that the retina is intact. In the same prospective study, some retinal tears were found only using careful indented peripheral retinal examination, and a visible Weiss ring was absent in a substantial proportion of eyes with tears.
What Is a Retinal Tear?
A retinal tear occurs when vitreous traction pulls strongly enough to create a break in the retina.
Fluid may pass through the tear and collect underneath the retina.
Without treatment, this may progress to a retinal detachment.
A symptomatic retinal tear may cause:
- Brief peripheral flashes
- A sudden increase in floaters
- A large new floater
- A shower of black dots
- Cobwebs
- Smoke or haze
- Blurred or missing vision
The eye is usually not painful.
Fresh symptomatic retinal tears are commonly treated using retinal laser or cryotherapy to form an adhesive scar around the break and reduce the risk of retinal detachment.
What Is Retinal Detachment?
Retinal detachment occurs when the retina lifts away from its normal position against the back wall of the eye.
Warning symptoms may include:
- New flashes
- Many new floaters
- A dark shadow
- A curtain or veil
- Missing peripheral vision
- Sudden blurred vision
- Progressive loss of the visual field
Retinal detachment is usually painless.
It is a medical emergency because a larger area may detach over time, increasing the risk of permanent visual loss.
Can Retinal Detachment Occur Without Flashes?
Yes.
Not every retinal tear or detachment causes the classic combination of flashes and floaters.
A patient may notice only:
- A shadow
- Reduced side vision
- General blur
- A missing area
- Reduced central vision
Some small detachments may initially cause no obvious symptoms.
The absence of flashes does not exclude a retinal detachment.
What Does a Curtain or Shadow Mean?
A curtain, veil or dark shadow suggests that part of the retina may no longer be functioning normally.
The shadow may:
- Begin at one side
- Descend from above
- Rise from below
- Progress towards the centre
- Remain fixed in one part of the field
Central vision may initially remain clear when only the peripheral retina is affected.
A curtain or shadow requires emergency retinal assessment even if:
- There is no pain
- The symptoms are mild
- The patient can still read
- The symptoms began several days earlier
Early treatment offers the best opportunity to protect the remaining vision.
What Does a Shower of Black Dots Mean?
A sudden shower of small black dots may represent:
- Red blood cells from vitreous haemorrhage
- Pigment cells released through a retinal tear
- Numerous new vitreous opacities during PVD
Patients may describe:
- Black pepper
- Soot
- Rain
- A swarm of insects
- Smoke
- Red or brown haze
Vitreous haemorrhage accompanying an acute PVD substantially increases concern for a retinal break.
A sudden shower of dots requires urgent examination of the peripheral retina.
Can a Tear Develop After the First Examination?
Yes.
The vitreous-detachment process may continue after the first visit.
The 2025 American Academy of Ophthalmology guideline notes that patients with acute PVD and no break detected initially still have a small chance of developing a retinal break in the following weeks. Other long-term studies have identified delayed tears months or occasionally longer after the first symptoms, particularly in eyes with risk factors such as lattice degeneration.
This is why selected patients require a repeat examination and why everyone should return immediately if they develop:
- More flashes
- More floaters
- A new shower of dots
- Blurred vision
- A shadow or curtain
- Missing peripheral vision
A previously normal examination does not make future changes safe to ignore.
Who Is at Greater Risk of a Retinal Tear or Detachment?
Risk factors include:
- Increasing age
- Moderate or high myopia
- Previous retinal tear or detachment
- Retinal detachment in a close family member
- Lattice degeneration
- Previous cataract or other intraocular surgery
- Significant eye trauma
- PVD
- Diabetic retinopathy
- Certain inherited retinal or vitreous conditions
People with these risk factors should seek prompt assessment when new flashes occur.
Why Does High Myopia Increase the Risk?
A highly myopic eye is generally longer from front to back.
This may be associated with:
- Earlier vitreous degeneration
- Earlier PVD
- A thinner peripheral retina
- Lattice degeneration
- Greater lifetime risk of retinal tears and detachment
LASIK, PRK, SMILE or ICL surgery may correct the refractive error, but these procedures do not shorten the eyeball or eliminate the retinal risks associated with the original myopia.
A patient with previous high myopia should therefore continue to respond urgently to new flashes and floaters.
Can Cataract Surgery Cause Flashes?
New flashes may occur after cataract surgery because:
- PVD develops or progresses
- Existing vitreous movement becomes more noticeable
- The clearer artificial lens makes visual phenomena easier to see
- A retinal tear or detachment develops
Previous cataract surgery is a recognised risk factor for retinal detachment.
New flashes, a marked increase in floaters or a shadow after cataract surgery should be examined promptly rather than attributed automatically to normal postoperative recovery.
Can YAG Laser Capsulotomy Cause Flashes?
YAG posterior capsulotomy treats clouding behind an intraocular lens.
Patients may briefly notice:
- Small moving particles
- New awareness of existing floaters
- Transient visual disturbance
A sudden increase in flashes or floaters after YAG treatment still requires retinal assessment because the symptoms may represent PVD, retinal traction or a retinal break.
Can Eye Trauma Cause Flashes?
Yes.
A blow to the eye may mechanically stimulate the retina and cause an immediate flash.
Trauma may also cause:
- PVD
- Retinal tear
- Retinal dialysis
- Vitreous haemorrhage
- Retinal detachment
- Inflammation
- Lens or other internal injury
Flashes following significant trauma require examination even when:
- The eye is not painful
- Vision seems relatively clear
- External redness is mild
- The injury occurred several days earlier
Retinal complications may be delayed.
Can Diabetes Cause Flashes?
Diabetic retinopathy may lead to:
- Vitreous haemorrhage
- Fibrous scar tissue
- Traction on the retina
- Tractional retinal detachment
- Retinal tears in selected situations
Patients may notice:
- Floaters
- Dark clouds
- Haze
- Blurred vision
- Flashes from vitreoretinal traction
- Missing vision
Advanced diabetic retinopathy can remain painless even when sight-threatening complications develop.
Can Inflammation Cause Flashes?
Yes.
Inflammation inside the eye, known as uveitis, can affect the retina and vitreous.
Possible symptoms include:
- Floaters
- Flashes
- Blurred vision
- Eye pain
- Redness
- Light sensitivity
Some posterior forms of uveitis may cause little external redness or pain.
New flashes accompanied by inflammatory symptoms require an examination to distinguish uveitis from PVD or retinal disease.
Can an Eye Infection Cause Flashes?
Infections involving the retina or vitreous may produce abnormal visual sensations, floaters and reduced vision.
Warning symptoms include:
- Eye pain
- Redness
- Light sensitivity
- Increasing blur
- New floaters or flashes
- Discharge
- Rapid visual deterioration
Infection inside the eye is particularly concerning after:
- Eye surgery
- Intravitreal injection
- Penetrating injury
- Severe immune suppression
These symptoms require emergency ophthalmic assessment.
Can Macular Disease Cause Flickering or Flashing?
Some macular conditions can produce:
- Flickering
- Shimmering
- Central flashes
- Distortion
- Wavy lines
- Central blur
Possible causes include:
- Vitreomacular traction
- Macular hole
- Macular oedema
- Age-related macular degeneration
These symptoms may differ from the brief peripheral lightning streaks of PVD.
New central distortion or flickering should be evaluated with a dilated retinal examination and commonly OCT imaging.
Are All Flashes Caused by the Eye?
No.
Flashing lights may originate from:
- The retina or vitreous
- The optic nerve
- The visual pathways
- The visual cortex of the brain
Migraine aura is the most common non-retinal explanation for recurrent patterned flashes.
Stroke and other neurological conditions may also cause visual symptoms, particularly when the disturbance is sudden, persistent or associated with weakness, confusion or speech difficulty.
Why Is It Important to Know Whether One Eye or Both Eyes Are Affected?
The distinction can help identify where the visual signal originates.
Symptoms Present in One Eye Only
These are more suggestive of a problem affecting:
- The vitreous
- Retina
- Optic nerve
- Blood supply to that eye
Examples include:
- PVD
- Retinal tear
- Retinal detachment
- Retinal vascular occlusion
- Retinal migraine
- Optic-nerve disease
Symptoms Present in Both Eyes
These are more suggestive of a disturbance affecting:
- The visual cortex
- The visual pathways behind the optic chiasm
- Migraine aura
- Selected neurological conditions
However, patients frequently find it difficult to determine whether the visual phenomenon is truly monocular or binocular.
How Can I Check Which Eye Is Affected?
While the symptom is occurring:
- Cover the right eye without pressing it.
- Observe whether the flashes remain.
- Cover the left eye.
- Observe again.
When the same pattern remains visible with either eye covered, the phenomenon is likely present in the visual field of both eyes and may originate from the brain rather than one eye.
When the phenomenon disappears completely after covering one particular eye, it is more likely monocular.
This test provides useful information but does not establish the diagnosis or replace medical assessment.
What Is Migraine Aura?
Migraine aura is a temporary neurological disturbance that commonly affects vision.
It may cause:
- Flashing lights
- Shimmering areas
- Zigzag lines
- Geometric or kaleidoscope patterns
- A spreading blind spot
- Sparkling edges
- Temporary distortion
Typical visual aura often:
- Develops gradually over several minutes
- Changes or spreads across the visual field
- Affects both eyes
- Lasts approximately 5 to 60 minutes
- May be followed by headache
- May occur without headache
Migraine aura may also be associated with numbness, tingling, dizziness or speech difficulty.
How Do Retinal Flashes Differ from Migraine Aura?
Retinal or Vitreous Flashes
More commonly:
- Affect one eye
- Appear as brief white or lightning-like arcs
- Occur near the edge of vision
- Last only moments
- Recur intermittently
- Are accompanied by new floaters
- Do not form an expanding geometric pattern
Migraine Aura
More commonly:
- Affects both eyes
- Appears as zigzags, shimmering or geometric patterns
- Gradually builds or spreads
- Lasts several minutes
- Resolves within approximately one hour
- May be followed by headache
- Can occur without headache
These are tendencies rather than absolute rules.
A first episode, an atypical pattern or uncertain one-eye symptoms should be medically assessed rather than self-diagnosed as migraine.
Can Migraine Aura Occur Without a Headache?
Yes.
This is sometimes called:
- Migraine aura without headache
- Acephalgic migraine
- Silent migraine
The visual phenomenon may be identical to the aura experienced before a migraine headache.
Because sudden visual symptoms can also result from retinal or vascular disease, a first episode—particularly later in life—should be evaluated rather than assumed to be migraine.
What Is Retinal Migraine?
Retinal migraine is a rare form of migraine producing temporary visual symptoms in one eye.
Possible symptoms include:
- Twinkling lights
- Flashes
- A blind spot
- Temporary reduction or loss of vision
Retinal migraine differs from typical migraine visual aura, which usually arises from the brain and affects the field of vision of both eyes.
Because temporary one-eye visual loss can also indicate retinal ischaemia or another serious eye condition, retinal migraine is a diagnosis of exclusion. A first monocular event should not be labelled “ocular migraine” without appropriate assessment.
When Might Visual Symptoms Indicate a Stroke?
Seek emergency medical care when flashing or disturbed vision is accompanied by:
- Facial drooping
- Weakness or numbness of an arm or leg
- Difficulty speaking
- Confusion
- Sudden loss of part of the visual field
- Double vision
- Severe dizziness or imbalance
- A sudden severe headache
- Loss of consciousness
Stroke-related symptoms generally begin suddenly.
Symptoms that resolve may represent a transient ischaemic attack and still require urgent medical assessment.
Can Brief Stars Appear After Rubbing the Eyes?
Yes.
Mechanical pressure on the eye may stimulate the retina and produce temporary spots, stars or flashes called phosphenes.
This does not mean that external light was present.
Deliberately pressing or rubbing the eye is not a safe way to test flashes and does not remove vitreous traction.
New spontaneous flashes—especially in one eye—should not be dismissed merely because similar sensations can occur after rubbing.
What Is an Afterimage?
After looking at a very bright light, camera flash or strong reflection, a temporary image may remain after the light source is gone.
An afterimage generally:
- Follows a clear bright-light exposure
- Corresponds to the shape or location of the light
- Gradually fades
- Does not recur spontaneously
Repeated flashes occurring without bright-light exposure are different and may need assessment.
Never look directly at the sun, a laser pointer or an intense artificial light source because retinal light injury can cause permanent central visual damage.
Why Are Retinal Flashes More Noticeable in the Dark?
A small flash is easier to notice against a dark background because there is less competing light.
Patients often first become aware of PVD-related flashes:
- At night
- In a dark bedroom
- When turning the head
- When looking towards a dim wall
- When moving the eyes rapidly
Flashes may still occur during daylight but be less obvious.
Do Flashes Cause Damage?
The flash itself does not damage the retina.
It is a visual signal indicating that the retina or visual pathways have been stimulated.
The underlying cause may be:
- Harmless
- Temporary
- Neurological
- Sight-threatening
The clinical importance comes from what is producing the flash—not from the flash sensation itself.
Do Flashes Go Away After a PVD?
They often become less frequent as the vitreous completes its separation and retinal traction reduces.
This may occur over:
- Days
- Weeks
- Several months
Floaters may persist longer than flashes.
Symptoms that increase again after improving should be reassessed because they may indicate new traction, bleeding or a delayed retinal tear.
Can Eye Drops Stop Retinal Flashes?
No routine eye drop can stop flashes caused by PVD or seal a retinal tear.
Eye drops may be used when flashes arise from another condition, such as:
- Uveitis
- Postoperative inflammation
- Raised eye pressure
- Selected infections
Do not self-start:
- Steroid drops
- Antibiotics
- Glaucoma drops
- Old postoperative medication
These do not treat ordinary vitreoretinal traction and may delay correct diagnosis.
Do Vitamins Prevent Retinal Tears?
No vitamin or supplement has been proven to:
- Stop a PVD
- Seal a retinal tear
- Prevent every retinal detachment
- Eliminate flashes
General health measures remain valuable, but supplements should not replace urgent retinal examination when new symptoms occur.
Can Moving the Eyes Stop the Flashes?
No.
Eye movement may temporarily increase awareness of vitreous traction because the gel shifts within the eye.
Trying to move the vitreous away through repeated rapid eye movements does not prevent a tear and may simply make the flashes more noticeable.
Should Exercise Be Avoided After New Flashes?
A person with new unexplained flashes should first undergo retinal assessment.
When the retina is intact and the PVD is uncomplicated, many patients can continue ordinary activity.
Individual restrictions may be recommended after:
- A retinal tear
- Retinal laser
- Retinal surgery
- Significant vitreous haemorrhage
- Eye trauma
- Findings indicating ongoing high-risk traction
The advice should be based on the retinal examination rather than on the symptom alone.
Can Flying Cause Retinal Flashes?
Commercial air travel does not normally cause PVD or retinal tears.
Patients may still first notice existing flashes while travelling because of:
- Dark cabin conditions
- Fatigue
- Changes in visual attention
Different rules apply after retinal surgery when an intraocular gas bubble is present. Flying with a gas bubble can cause a dangerous pressure rise and must be avoided until the surgeon confirms that the gas has disappeared.
How Are Flashes of Light Examined?
Visual Acuity
Each eye is tested separately.
Good central acuity does not exclude a peripheral retinal tear or early detachment.
Pupil Examination
The pupils are assessed for:
- Symmetry
- Light reaction
- A relative afferent pupillary defect
An abnormal response may indicate significant retinal or optic-nerve dysfunction.
Slit-Lamp Examination
The clinician checks:
- Cornea
- Anterior chamber
- Iris
- Lens
- Anterior vitreous
Possible warning findings include:
- Inflammation
- Blood
- Pigment cells
- Signs of trauma
- Postoperative complications
Dilated Retinal Examination
Dilating drops enlarge the pupil so the vitreous, macula, optic nerve and peripheral retina can be examined.
The doctor looks for:
- PVD
- Retinal tear
- Retinal hole
- Vitreous haemorrhage
- Pigment cells
- Lattice degeneration
- Retinal detachment
- Inflammation
- Macular traction
A dilated examination is the key test for new retinal-type flashes.
What Is Scleral Indentation?
During scleral indentation, the clinician applies gentle pressure to the outside of the eye through the eyelid or anaesthetised conjunctiva.
This brings the far peripheral retina into view.
It can help detect tears that are difficult to see with ordinary examination alone.
The procedure may feel uncomfortable but should be brief.
Prospective research has shown that some retinal tears are identified only using careful indented indirect ophthalmoscopy.
Is an Optos or Wide-Field Photograph Enough?
Wide-field imaging can document a large area of retina and is useful for:
- Recording findings
- Comparing future examinations
- Identifying many peripheral lesions
- Patient education
However, a photograph may miss:
- A small far-peripheral tear
- A tear obscured by lashes or eyelids
- Dynamic vitreoretinal traction
- Subtle elevation around a break
- Areas outside the captured field
When acute flashes are present, imaging should support rather than automatically replace a careful dilated peripheral retinal examination.
When Is Ultrasound Used?
Eye ultrasound may be required when the retinal view is obscured by:
- Vitreous haemorrhage
- Dense cataract
- Corneal opacity
- Severe inflammation
Ultrasound can help identify:
- Retinal detachment
- PVD
- Vitreous haemorrhage
- Larger retinal tears
- Intraocular masses
A normal ultrasound cannot exclude every small retinal break, so follow-up and return precautions remain important.
When Is OCT Useful?
OCT produces cross-sectional images of the retina and macula.
It may help when flashes are associated with:
- Central distortion
- Vitreomacular traction
- Macular hole
- Epiretinal membrane
- Macular oedema
- Macular degeneration
A normal macular OCT does not exclude a peripheral retinal tear.
Will Brain Imaging Be Needed?
Most patients with typical PVD-related flashes do not require brain imaging.
Neurological investigation may be considered when symptoms are:
- Present in both eyes
- Persistent
- Associated with a visual-field defect
- Accompanied by weakness or speech difficulty
- Associated with seizures or altered awareness
- Atypical for both PVD and migraine
- Associated with abnormal neurological examination findings
The required investigation may include medical assessment, blood tests, CT, MRI or vascular imaging depending on the suspected cause.
How Are Retinal Flashes Treated?
Treatment depends entirely on the cause.
Uncomplicated PVD
Usually requires:
- Observation
- Retinal warning advice
- Follow-up when indicated
The flashes normally diminish as the vitreous separation stabilises.
Retinal Tear
Usually treated using:
- Retinal laser photocoagulation
- Cryotherapy
The treatment creates adhesion around the break.
Retinal Detachment
May require:
- Pneumatic retinopexy
- Scleral buckle surgery
- Pars plana vitrectomy
- Retinal laser or cryotherapy
- A combination of procedures
Uveitis or Infection
Requires treatment directed at the underlying inflammatory or infectious cause.
Migraine Aura
Management may include:
- Trigger identification
- Acute migraine treatment
- Preventive treatment for frequent attacks
- Neurological review when the diagnosis is uncertain
Does Retinal Laser Stop the Flashes Immediately?
Not necessarily.
Retinal laser seals the tissue around a tear but does not instantly eliminate:
- PVD
- Vitreous movement
- Existing traction elsewhere
- Floaters
Flashes may persist temporarily after successful laser.
New or increasing symptoms after treatment still require reassessment because additional tears can occasionally develop elsewhere.
Does a PVD Require Surgery?
An uncomplicated PVD does not usually require surgery.
Treatment is directed at complications such as:
- Retinal tear
- Retinal detachment
- Non-clearing vitreous haemorrhage
- Macular hole
- Significant vitreomacular traction
Vitrectomy may occasionally be considered for persistent severe floaters, but it is not performed simply to treat brief flashes from an uncomplicated PVD.
Frequently Asked Questions
Are flashes always an emergency?
Not every flash is caused by an emergency.
New spontaneous flashes—especially in one eye—require prompt assessment because retinal traction and migraine may look similar to the patient.
Is one brief flash dangerous?
A single flash may be caused by movement, pressure or vitreous traction.
A new unexplained episode should be considered together with:
- Age
- Floaters
- Myopia
- Surgery
- Trauma
- Recurrence
Can retinal tears cause only flashes without floaters?
Yes.
A tear may cause:
- Flashes alone
- Floaters alone
- Both symptoms
- Blur or a missing area
Can retinal detachment occur without flashes?
Yes.
A patient may notice only a curtain, shadow or reduced vision.
Are flashes from retinal detachment painful?
Usually not.
The retina does not normally produce the type of pain caused by the cornea or inflammation.
Can flashes happen in a healthy eye?
Brief phosphenes may occur after pressure or bright-light exposure.
Recurrent spontaneous flashes should not be labelled normal without assessment.
Why do I see flashes when moving my eyes?
Eye movement causes the vitreous to shift.
When the vitreous is pulling on the retina, this movement may trigger a flash.
Why are the flashes at the side of my vision?
PVD commonly stimulates the peripheral retina, which is perceived as light on the opposite side of the visual field.
Why do I see flashes only at night?
They may be occurring during the day but are easier to notice against a dark background.
Why are my flashes white?
Mechanical retinal stimulation is commonly interpreted as a white or pale flash, although patients may describe other colours.
Do coloured zigzags mean migraine?
They are suggestive of migraine aura, particularly when they gradually expand and are visible with either eye covered.
A first or atypical event should still be assessed.
Can migraine aura affect only one side of vision?
Yes.
A brain-based aura may affect the left or right half of the visual field but remain present in both eyes when tested separately.
This can be mistaken for a symptom in only one eye.
Does migraine aura always cause headache?
No.
Visual aura can occur without headache.
Is retinal migraine common?
No.
True retinal migraine is considered rare and affects one eye. Other retinal and vascular causes must first be excluded.
Can stroke cause flashing lights?
Stroke more commonly produces sudden missing or blurred vision, but positive visual symptoms may occur.
Emergency assessment is essential when visual disturbance is accompanied by neurological symptoms.
Can high eye pressure cause flashes?
Ordinary chronic high pressure does not typically cause flashes.
Acute angle closure more commonly produces:
- Eye pain
- Redness
- Misty vision
- Halos
- Headache
- Nausea
Can glaucoma cause flashes?
Chronic glaucoma does not usually cause flashing lights.
New flashes in a patient with glaucoma still require assessment for retinal, migraine or neurological causes.
Can dry eye cause flashes?
Dry eye causes:
- Fluctuating blur
- Glare
- Burning
- Grittiness
It does not normally cause brief retinal-type lightning flashes.
Can cataract cause flashes?
Cataract usually causes:
- Haze
- Glare
- Halos
- Poor night vision
Mobile lightning-like flashes are more suggestive of vitreoretinal traction or another visual phenomenon.
Can flashes continue after a normal retinal examination?
Yes.
Uncomplicated PVD flashes may continue for weeks or months.
Return immediately if they increase or are joined by floaters, blur, a curtain or field loss.
Does a normal examination guarantee that no tear will appear later?
No.
A delayed tear can occasionally develop as the vitreous continues separating.
Should both eyes be examined?
Yes.
The symptomatic eye requires careful examination, and the fellow eye may have:
- A previous unnoticed PVD
- Lattice degeneration
- Retinal holes
- Other risk factors
Can I drive to the appointment?
Do not drive when:
- Vision is reduced
- A shadow is present
- The flashes are distracting
- Both eyes are affected
- Neurological symptoms are present
Dilating drops used during the examination may also temporarily affect vision.
A Practical Urgency Guide
Seek Emergency Eye Care Immediately
- A curtain or dark shadow
- Missing peripheral or central vision
- Sudden significant visual loss
- Flashes with a shower of black dots
- Rapidly worsening flashes and floaters
- Symptoms after major eye trauma
- Severe postoperative pain, redness or reduced vision
Seek Emergency Medical Care
- Flashes or visual loss with facial droop
- Arm or leg weakness
- Difficulty speaking
- Confusion
- Severe imbalance
- A sudden severe headache
- Loss of consciousness or seizure
Arrange Prompt Dilated Retinal Assessment
- New flashes in one eye
- New flashes with floaters
- A new large ring or cobweb
- Flashes in a highly myopic eye
- Flashes after cataract or YAG surgery
- Flashes following minor trauma
- A sudden change in a previously stable pattern
Routine Review May Be Appropriate
- A previously diagnosed stable migraine pattern
- No change from prior episodes
- No one-eye field loss
- No curtain, new floaters or visual reduction
- No new neurological symptoms
A first or atypical episode should not be placed automatically into the routine category.
A Practical Clinical Approach
Step 1: Clarify the Appearance
- Lightning streak
- Camera flash
- Spark
- Zigzag
- Shimmer
- Expanding pattern
- Coloured shape
Step 2: Determine the Timing
- Fraction of a second
- Recurrent brief flashes
- Gradual build-up over minutes
- Persistent disturbance
Step 3: Determine Whether One or Both Eyes Are Affected
Test each eye separately while the symptom is present.
Step 4: Look for Retinal Warning Symptoms
- New floaters
- Shower of dots
- Curtain
- Shadow
- Missing vision
- Blur
Step 5: Identify Risk Factors
- Age over 50
- High myopia
- Cataract surgery
- Previous retinal tear or detachment
- Lattice degeneration
- Trauma
- Diabetes
- Uveitis
Step 6: Check for Neurological Symptoms
- Weakness
- Numbness
- Speech difficulty
- Confusion
- Severe headache
- Imbalance
Step 7: Examine the Peripheral Retina
Perform a dilated retinal examination, using scleral indentation when clinically indicated.
Step 8: Treat the Underlying Cause
- Observe uncomplicated PVD
- Laser or freeze a retinal tear
- Operate on retinal detachment
- Treat inflammation or infection
- Investigate neurological or vascular symptoms
- Manage migraine when other causes have been excluded
Step 9: Provide Clear Return Precautions
The patient should know that a worsening pattern overrides any scheduled follow-up date.
Common Myths About Flashes of Light
“Flashes are always migraine.”
False.
Vitreous traction and retinal tears commonly cause flashes.
“Retinal detachment always causes a curtain immediately.”
False.
Flashes or floaters may precede the curtain.
“If there is no pain, the retina must be healthy.”
False.
Retinal tears and detachments are usually painless.
“One normal examination means I cannot develop a later tear.”
False.
The vitreous may continue separating after the first examination.
“Retinal laser removes the flashes.”
False.
Laser seals a tear but may not immediately eliminate ongoing vitreous movement.
“Flashes in both eyes are always harmless.”
False.
They may represent migraine, but sudden binocular visual disturbance with neurological symptoms may indicate a stroke or another neurological problem.
“Every one-eye flash is retinal migraine.”
False.
Retinal migraine is rare. Retinal traction, tear and vascular disease must be excluded.
“Rubbing the eye can move the vitreous into a safer position.”
False.
Rubbing does not prevent a retinal tear and may injure the eye.
“Clear central vision means there is no retinal detachment.”
False.
A peripheral detachment may initially spare central vision.
“Old steroid or antibiotic drops will settle the flashes.”
False.
These drops do not treat PVD or seal a retinal tear.
The Bottom Line
Flashes of light are visual signals produced without an external light source.
The commonest ocular cause in adults is posterior vitreous detachment.
As the vitreous separates from the retina, it may produce:
- Brief peripheral flashes
- New floaters
- A ring or cobweb
- A shower of dots when bleeding occurs
Most PVDs are uncomplicated.
However, some cause:
- Retinal tears
- Vitreous haemorrhage
- Retinal detachment
- Macular traction or holes
Migraine aura is another common cause of flashing visual symptoms. It more often:
- Affects both eyes
- Produces zigzags or shimmering patterns
- Builds gradually
- Lasts 5 to 60 minutes
- May occur with or without headache
New flashes require particular urgency when accompanied by:
- New floaters
- A shower of black dots
- Blurred vision
- A curtain or shadow
- Missing peripheral vision
- Eye trauma
- Recent eye surgery
Neurological emergency care is required when visual symptoms are accompanied by:
- Weakness
- Numbness
- Speech difficulty
- Confusion
- Severe imbalance
- Sudden severe headache
The appearance of a flash cannot reliably reveal whether the retina is merely being tugged or has already torn. New one-eye flashes should be treated as a retinal warning symptom until a dilated examination shows otherwise.
References
- National Eye Institute. Vitreous Detachment. Updated December 2024.
- National Eye Institute. Retinal Detachment. Updated November 2025.
- American Academy of Ophthalmology. Posterior Vitreous Detachment, Retinal Breaks and Lattice Degeneration Preferred Practice Pattern. 2025.
- American Academy of Ophthalmology. Flashes of Light. Updated April 2024.
- Nixon TRW, et al. Posterior Vitreous Detachment and Retinal Tear: A Prospective Study of Community Referrals. Eye. 2024.
- Jindachomthong KK, et al. Incidence and Risk Factors for Delayed Retinal Tears After an Acute, Symptomatic Posterior Vitreous Detachment. Ophthalmology Retina. 2023.
- Vangipuram G, et al. Timing of Delayed Retinal Pathology in Patients Presenting with Acute Posterior Vitreous Detachment. Ophthalmology Retina. 2023.
- Moorfields Eye Hospital. Flashes and Floaters: Diagnosis and Treatment.
- NHS. Migraine.
- American Migraine Foundation. Migraine Aura Without Headache.
- American Migraine Foundation. Retinal Migraine: Symptoms, Causes and Treatment.
- American Migraine Foundation. Demystifying Migraine with Aura.
- Stroke Association. Stroke Signs and Symptoms.
- National Eye Institute. Diabetic Retinopathy. Updated September 2025.
- National Eye Institute. Cataract Surgery: Warning Symptoms After Surgery.
