Eye flashes are brief bursts of light you see even though no actual light source is there. They can look like lightning streaks, sparks, or flickering spots, and they happen when something physically tugs on the retina, the light-sensitive tissue lining the back of your eye. Most of the time, flashes are harmless and tied to normal aging, but in roughly 14% of people who show up to an eye doctor with new flashes or floaters, a retinal tear is found.
Why Flashes Happen
Your eye is filled with a clear, gel-like substance called the vitreous. When you’re young, this gel is thick and firmly attached to the retina. As you age, it slowly shrinks and liquefies, pulling away from the retinal surface. Each time the vitreous tugs on the retina, the retina responds the only way it knows how: by firing a light signal to your brain. You perceive that signal as a flash, even though no light entered your eye. The medical term for this is photopsia.
The most common trigger is posterior vitreous detachment, or PVD, which is essentially the vitreous peeling away from the retina over time. More than half of people over 50 have some degree of PVD, and by the time people reach their 70s and 80s, roughly two-thirds do. It’s one of the most predictable changes the eye undergoes with age.
What Flashes Look Like
Flashes from vitreous traction are typically quick, like a camera flash going off at the edge of your vision. They tend to appear in one eye at a time, last only a fraction of a second, and come and go unpredictably. You’re more likely to notice them in dim lighting or when your eyes are closed, because there’s less competing visual input. They don’t usually block your vision on their own, though they may show up alongside floaters, those small dark specks or squiggly lines drifting across your field of view.
Flashes From Migraines Look Different
Not all flashes come from the retina. Migraine auras produce their own kind of visual light show, and the two are worth telling apart.
Migraine-related flashes tend to last much longer, up to about 30 minutes, and they typically affect both eyes at the same time. They often start small and grow larger, with jagged, geometric edges that shimmer or pulse in rhythm with your heartbeat. You may also notice a blank spot in your vision that shrinks as the flashes fade. A headache or nausea sometimes follows, though not always. These flashes rarely come with floaters.
Retinal traction flashes, by contrast, are brief and random, happen in just one eye, and often appear alongside new floaters. If your flashes fit the migraine pattern, especially the geometric shapes and gradual expansion across both eyes, you’re likely dealing with a neurological event rather than a retinal one.
Who Gets Flashes More Often
Age is the biggest risk factor. The vitreous naturally degrades over decades, so flashes become increasingly common after 50. But several other factors speed up the process:
- Severe nearsightedness (myopia). Highly nearsighted eyes are longer than average, which stretches the vitreous and makes it more likely to pull away from the retina earlier in life.
- Previous eye surgery. Procedures like cataract removal can alter the vitreous structure and increase the chance of detachment.
- Eye trauma. A blow to the eye or head can jostle the vitreous enough to create sudden traction on the retina.
If you fall into any of these categories and start noticing new flashes, it’s worth having your eyes examined sooner rather than later.
When Flashes Signal Something Serious
Most flashes are a side effect of the vitreous doing what it naturally does with age. But the same pulling force that causes harmless flashes can occasionally tear the retina, and a torn retina can lead to retinal detachment if fluid seeps behind it and lifts it away from the back of the eye. Retinal detachment is a medical emergency that can cause permanent vision loss if not treated quickly.
The warning signs to watch for are a combination of symptoms that escalate beyond occasional flashes:
- A sudden surge of new floaters. Seeing a few floaters is normal. Suddenly seeing many more than usual is not.
- Persistent or intensifying flashes in one eye.
- A dark shadow or curtain effect creeping across your field of vision from any direction.
- A noticeable drop in clarity that comes on suddenly rather than gradually.
Any of these symptoms, especially in combination, calls for an urgent eye exam or an emergency room visit. The difference between a retinal tear and a full detachment can be a matter of hours or days, and catching a tear early makes treatment far simpler.
How Retinal Tears Are Treated
If a tear is found, the standard approach is laser treatment or a freezing procedure called cryopexy. Both work by creating a seal around the tear so fluid can’t get behind the retina. The procedures are typically done in an office or outpatient setting, and the goal is to prevent the tear from progressing to a detachment. Recovery is generally straightforward, though your doctor will likely schedule follow-up visits to make sure the seal holds.
When no tear is found, which is the case for the majority of people who get checked, the flashes usually resolve on their own over weeks to months as the vitreous finishes separating from the retina. Some people continue to see occasional flashes for longer, particularly in dark environments, but they tend to become less frequent and less noticeable over time.