Flashes of Light in Your Vision: What They Mean and When It’s an Emergency
Short answer: flashes of light that look like lightning streaks usually mean the gel inside your eye is tugging on the retina, a common part of aging. Most of the time it’s harmless, but in about 1 in 7 people who see an eye doctor for sudden flashes or floaters, it has torn the retina. New flashes mean seeing an eye doctor as soon as possible, and a shadow over your vision means going right away.
Normal or urgent?
- New flashes in one eye: get a dilated eye exam as soon as possible, ideally the same day
- Flashes plus a shower of new floaters, or a shadow or curtain: an emergency; see an eye doctor or go to the ER now
- Shimmering zigzags that spread and fade within an hour: more typical of a migraine aura
- Already told it’s a harmless vitreous detachment? Go back if symptoms change
- No supplement or eye drop has been shown to prevent or stop flashes
Is it your eye or a migraine?
Two very different things cause most flashes, and they usually look different. The descriptions below come from the American Academy of Ophthalmology (AAO).
| From the retina (vitreous pulling) | From a migraine aura | |
|---|---|---|
| What it looks like | Brief flashes or lightning streaks, like “seeing stars” | Jagged lines, shimmering spots or “heat waves” that spread |
| How long | Brief, but can keep coming back for weeks or even months | Spreads and fades, lasting up to about an hour |
| Which eye | Usually one eye | One or both eyes, often the same area of both |
| Often comes with | New floaters; sometimes a shadow or blurred vision | A headache, though not always |
A simple check: when it happens, cover one eye, then the other. Flashes that show up in only one eye point to the retina of that eye. A shimmering pattern that stays in the same spot whichever eye you cover is more typical of a migraine aura, which starts in the brain rather than the eye.
That check helps you describe what’s happening; it can’t rule out a retinal tear. Only a dilated eye exam can.
Why flashes happen
The inside of your eye is filled with a clear gel called the vitreous, which is attached to the retina. The AAO explains that flashes happen when the vitreous rubs or pulls on the retina.
With age, the vitreous becomes more liquid, shrinks and eventually pulls away from the retina. This is called a posterior vitreous detachment (PVD). The AAO calls it a normal part of aging that happens to most people by age 70. Many people notice nothing; others see flashes and new floaters for a while.
In most people, a PVD causes no lasting harm. The risk is that the gel pulls hard enough to tear the retina, and that’s what the eye doctor checks for.
When flashes are an emergency
The National Eye Institute (NEI) calls a detached retina a medical emergency. Go to your eye doctor or the emergency room right away if flashes come with any of these:
- A lot of new floaters (small dark spots or squiggly lines)
- A dark shadow or “curtain” on the side or in the middle of your vision
- Blurred or reduced vision in that eye
Why the rush? A retinal tear can usually be sealed, but if it isn’t treated, the retina can detach and permanent vision loss can follow. Caught early, treatment works well.
Among people who saw an eye doctor for sudden new floaters or flashes, 14% had a retinal tear. A feeling that vision had gotten worse was the symptom most strongly linked to a tear.
Hollands H, et al. “Acute-onset floaters and flashes: is this patient at risk for retinal detachment?” JAMA, 2009 (review of 17 studies).
What to tell the eye doctor
When you call, say clearly that you have new flashes of light, and mention any new floaters or shadow. That helps them decide how soon to see you.
Before you call, note down:
- Which eye (cover one, then the other)
- When the flashes started, and how often they happen
- Whether you also have new floaters, and roughly how many
- Any shadow, curtain or blurred area in your vision
- Whether you’re very nearsighted, have had eye surgery or a recent eye injury
Take a screenshot of this list. It gives the eye doctor what they need to judge how urgent your visit is.
At the visit, expect drops to widen your pupils so the doctor can examine the whole retina.
Told it’s “just a vitreous detachment”? Watch for changes
A normal first exam is reassuring, but it isn’t the end of the story. In the same JAMA review, people first diagnosed with an uncomplicated PVD still had a 3.4% chance of a retinal tear within 6 weeks. The risk was higher if they later noticed 10 or more new floaters or a drop in vision.
- Keep your follow-up appointment if one is booked. EyeWiki, the AAO’s clinical reference, notes that a repeat dilated exam about a month after a new PVD is commonly recommended.
- Go back right away if you get a burst of new floaters, more flashes, a shadow or blurred vision.
Flashes can come and go for weeks or even months, and floaters usually become less noticeable over time.
Who’s at higher risk of a retinal detachment
The NEI lists these as raising the risk:
- Extreme nearsightedness
- Previous eye surgery, including cataract surgery
- A serious eye injury
- A family history of retinal detachment
- Diabetes-related eye disease
- A posterior vitreous detachment
If any of these apply, don’t wait on new flashes. Related reading: eye floaters: when they’re normal and signs of cataracts.
How tears and detachments are treated
If there’s no tear, flashes from a PVD usually need no treatment. If the doctor finds a tear, the AAO says it can be sealed with laser or a freezing treatment. A detached retina needs surgery.
The NEI says treatment for retinal detachment is ultimately successful for about 9 out of 10 people, and works best when the detachment is caught early. That’s the whole reason to act fast.
Can supplements help flashes?
No. We found no evidence that any supplement or eye drop prevents flashes, reattaches the vitreous or lowers the risk of a retinal tear, and neither the NEI nor the AAO recommends one for this. Be wary of products that claim otherwise.
What protects your sight here is a prompt eye exam, not a pill.
Frequently asked questions
What causes flashes of light in the eye?
Are flashes of light in the eye an emergency?
How do I know if flashes are from a migraine?
Do flashes of light go away?
Can a retinal tear be treated?
Can supplements stop flashes of light?
The bottom line
Flashes of light usually come from the aging gel inside the eye tugging on the retina, and most of the time that’s harmless. But you can’t tell the harmless cases from a retinal tear at home, and about 1 in 7 people who get checked for sudden flashes or floaters have one. New flashes mean a dilated eye exam as soon as possible; flashes with a shadow, a shower of floaters or blurred vision mean going now. Caught early, tears and detachments are very treatable.
This article is for informational purposes and isn’t a substitute for medical advice. New flashes of light, a shower of new floaters, a shadow over your vision or sudden blurred vision need an eye care provider right away.
Sources
- American Academy of Ophthalmology. “What Are Floaters and Flashes?”
- American Academy of Ophthalmology. “What Is a Posterior Vitreous Detachment?”
- American Academy of Ophthalmology. “What are the bright, wavy lines that were in my vision for a half-hour?”
- National Eye Institute. “Retinal Detachment.”
- Hollands H, Johnson D, Brox AC, et al. “Acute-onset floaters and flashes: is this patient at risk for retinal detachment?” JAMA, 2009;302(20):2243-2249.
- EyeWiki (American Academy of Ophthalmology). “Posterior Vitreous Detachment.”
Photo: Johannes Plenio / Unsplash