What Causes Flashing Lights in the Corner of Your Eye?
The most common cause of flashing lights in your peripheral vision is a change in the vitreous, the clear, jelly-like substance that fills the inside of your eye. As you age, this gel slowly shrinks and pulls away from the retina, the light-sensitive tissue at the back of the eye.
When the vitreous tugs on the retina during this separation, it stimulates the retinal cells. Your brain interprets that stimulation as light, even though no light is actually entering your eye. This is why you see a flash or a sparkle. This process is known as posterior vitreous detachment (PVD).
PVD is a normal part of aging for many people, often occurring after age 50. For most, it happens without any damage. The flashes usually stop once the vitreous has fully detached from the retina, which can take a few weeks or months.
When Flashing Lights Indicate a Retinal Tear
Sometimes the vitreous does not separate cleanly. If it is firmly stuck to the retina, the pulling force can tear the retina. A retinal tear is a serious problem because it allows fluid to seep underneath the retina, potentially causing it to detach.
The flashes from a retinal tear are often more persistent or frequent. You might also notice new floaters—small dark shapes, lines, or cobwebs that drift across your vision. A sudden shower of floaters, especially accompanied by flashes, is a classic warning sign of a tear.
A torn retina does not heal on its own. If you have these symptoms, you need an eye exam as soon as possible. An ophthalmologist can treat a tear, often with laser or freezing therapy, to seal it and prevent a detachment.
Retinal Detachment: A Medical Emergency
A retinal detachment occurs when the retina is pulled away from the back wall of the eye, cutting off its blood supply. Without prompt treatment, this can lead to permanent vision loss in that eye.
Flashing lights can be an early symptom of a detachment. As the detachment progresses, you may notice a shadow or a curtain-like effect that moves across your field of vision. This is not a symptom to wait out. If you experience a sudden increase in flashes, a new large floater, or a shadow in your vision, you should see an eye doctor immediately.
The American Academy of Ophthalmology advises that a sudden onset of flashes and floaters warrants an urgent dilated eye exam. Do not wait to see if it improves on its own. Prompt treatment is the single most important factor in preserving vision after a retinal detachment.
Other Causes of Peripheral Light Flashes
While vitreous traction is the most common cause, other conditions can produce similar visual symptoms.
Migraine with Aura can cause visual disturbances that are often mistaken for eye problems. An ocular migraine or a migraine aura can produce flashing lights, zigzag lines, or blind spots. These symptoms usually develop over several minutes and typically resolve within an hour. They can occur with or without a headache following them. If the visual disturbance moves across your field of vision and disappears within 30-60 minutes, a migraine is a likely explanation.
Pressure on the retina from other sources can also create flashes. For example, rubbing your eyes vigorously can cause you to see stars or brief flashes of light. This is mechanical pressure stimulating the retina, and it is typically harmless.
Some medications can cause light sensitivity or visual disturbances, though this is less common than floaters or flashes from vitreous changes. If you suspect a medication side effect, discuss it with your prescribing doctor.
Why You Should Not Rub Your Eyes
When you rub your eyes, you are applying physical pressure to the eyeball. This pressure can mechanically stimulate the retina, causing you to see flashes or “stars.” While an occasional rub is unlikely to cause harm, frequent or forceful rubbing is not a good idea.
In eyes where the vitreous is already pulling on the retina, aggressive rubbing could theoretically increase the risk of a tear. There is no solid evidence that normal eye rubbing causes a retinal tear in a healthy eye. However, if you are already experiencing flashes or floaters, you should avoid rubbing your eyes and see an eye care professional.
What to Expect During an Eye Exam
If you go to an eye doctor for flashes, they will perform a comprehensive exam. The key part of this exam is dilating your pupils. Drops are placed in your eyes to widen the pupil, allowing the doctor to see the retina clearly at the back of the eye.
The doctor will look specifically for any tears or holes in the retina and assess the health of the vitreous. The exam is not painful, though the dilation drops may cause a stinging sensation for a few seconds. Your vision will be blurry and your eyes will be sensitive to light for a few hours afterward, so you will need someone to drive you home.
The doctor will also check your peripheral vision and measure the pressure inside your eye. This exam is the only reliable way to distinguish between a harmless PVD and a dangerous retinal tear.
When to See an Eye Doctor Immediately
You should seek urgent care from an eye specialist if you experience any of the following:
- A sudden increase in the number of floaters you see
- A single large floater that appears suddenly
- Flashes of light that are new, frequent, or persistent
- A shadow, dark curtain, or gray area that blocks part of your vision
- A sudden decrease in vision
These symptoms can indicate a retinal tear or detachment. Time is critical. If you have these symptoms, do not wait for a routine appointment. Contact an ophthalmologist or go to an emergency room that has eye care services.
Why Do I See Lights In The Corner Of My Eye?
The phrase “lights in the corner of my eye” usually describes flashes that occur in your peripheral vision. This location is significant because the vitreous is often most strongly attached to the retina near the edges of the eye. When traction occurs, it is frequently felt in the side vision first.
These flashes often appear as brief, lightning-like streaks or arcs. They may be more noticeable in a dark room or when you move your eyes quickly. The shape and location of the flashes can help your doctor determine whether they are caused by vitreous traction or a neurological issue like a migraine.
The crucial point is that any new onset of flashing lights in your peripheral vision should be evaluated by an eye care professional. While the cause is often a benign aging change, the risk of a retinal tear makes an evaluation essential.
Frequently Asked Questions
Are flashing lights in the corner of my eye always an emergency?
No. Flashes are often caused by the vitreous gel pulling on the retina, which can be harmless. However, because they can also signal a retinal tear, a sudden onset of flashes warrants an urgent eye exam.
How long do flashing lights last before they go away?
If caused by posterior vitreous detachment, flashes may come and go for several weeks or months until the gel fully separates. Migraine-related flashes typically last between 20 and 60 minutes.
Can stress or anxiety cause flashing lights in my eyes?
Stress alone does not cause flashes from the retina. However, stress can trigger a migraine with aura, which can produce visual symptoms like flashing lights.
What is the difference between a floater and a flash?
A floater is a dark spot or strand that drifts across your vision and follows your eye movements. A flash is a brief spark or streak of light that appears without an external light source.
