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Jeremy Lopez

Why Do I Suddenly See Flashes of Light or Floaters?

New flashes of light or floaters are often caused by age-related changes in the gel inside your eye, called the vitreous, which can pull away from the retina in a process known as posterior vitreous detachment.

Why Do I Suddenly See Flashes of Light or Floaters?
SymptomsVision Changeswhen-to-worry
Written By: DocAi Health Editorial Team
Last Updated: 2026-09-30
Medical Disclaimer: This article is for general informational and educational purposes only and is not medical advice. It does not create a doctor-patient relationship and is not a substitute for professional diagnosis or treatment by a qualified healthcare provider. Never disregard or delay seeking professional medical advice because of something you have read here. If you think you may have a medical emergency, call 911 or your local emergency number right away. Health information can change and this guidance is general and US-focused, so consult a licensed clinician in your own country about your specific situation.
New flashes of light or floaters are often caused by age-related changes in the gel inside your eye, called the vitreous, which can pull away from the retina in a process known as posterior vitreous detachment. The same symptoms can also occur with a retinal tear or detachment, and a tear left untreated can progress to a detachment that threatens your vision, so sudden new flashes or floaters need an urgent eye examination. This article explains what causes flashes and floaters, how a migraine can look similar, and which signs need urgent eye care.

What Can Cause Flashes and Floaters

Your eye is filled with a clear, gel-like substance called the vitreous, and it fills the space between the lens and the retina. As you get older, the vitreous slowly changes texture. It shrinks and becomes more liquid in some areas while clumps of collagen fibers form in others. Those clumps cast tiny shadows on the retina, and your brain reads those shadows as floaters: specks, threads, or faint rings that drift across your field of view when you move your eyes.
Flashes happen through a different mechanism. As the shrinking vitreous pulls on the retina, that mechanical tug stimulates the light-sensing cells the same way actual light would, and your brain interprets the signal as a flash even though no light is involved. People often describe it as a brief streak, spark, or flicker off to the side of their vision, most noticeable in dim light. The American Academy of Ophthalmology notes that flashes can come and go for weeks or even months, and that you should call an ophthalmologist right away if you notice a lot of new floaters or a lot of flashes.
This process is called a posterior vitreous detachment, or PVD. The American Academy of Ophthalmology describes it as a common part of aging that is often uncomplicated, but new flashes or floaters still need an eye examination to rule out a retinal tear or detachment. The National Eye Institute lists a lot of new floaters that appear suddenly, sometimes with flashes of light, among the signs of a retinal tear or detachment, which is why the same symptom needs to be checked even when it often turns out to be routine aging.

Why the Vitreous Separates From the Retina

The vitreous is attached to the retina by millions of microscopic fibers. As the gel liquefies with age, enough of those fibers break that it pulls free from the back of the eye. Symptoms often begin suddenly, with a new increase in floaters, flashes, or both, although many people with a PVD notice nothing at all.
The American Academy of Ophthalmology notes that a PVD usually happens to most people by the age of 70. It can happen earlier in people who are nearsighted, who have had cataract or other eye surgery, who have diabetes, or who have had an injury to the eye.
In many cases the vitreous separates cleanly and the retina is left intact. In a smaller number of people, the vitreous stays stuck to a weak spot on the retina during the pull, and the traction tears a hole in the retinal tissue instead of releasing cleanly. That tear is what turns a normal aging process into an eye emergency, because fluid can seep through the tear and lift the retina off the back of the eye.

When Flashes Point to a Migraine Instead of an Eye Problem

Not every flash of light comes from the eye itself. Migraine with aura produces visual symptoms that can look similar at first: shimmering, zigzag lines, a growing blind spot, or flickering light. Timing and shape can help tell them apart, though not perfectly. A migraine aura often develops gradually, spreads across the visual field, and usually affects the visual field seen by both eyes because it originates in the brain, although people may perceive it as being on one side. The American Academy of Ophthalmology says these flashes may last up to 60 minutes and can occur with or without a headache. If your flashes come with head pain, especially on one side, our guide to headache behind the left eye with nausea covers migraine patterns in more depth, and Migraine or Something More Serious? explains how to tell the difference.
A flash from vitreous traction, by contrast, is often brief, is usually noticed in one eye, often appears off to the side of your vision, and is not tied to a headache. Those features are only a guide. If you are not sure whether a visual symptom affects one eye or both, do not use that distinction to rule out an eye problem. A first-ever visual aura, a major change from your usual migraine pattern, or sudden vision loss warrants medical evaluation rather than assuming it is migraine.

Who Notices New Floaters and Flashes First

Some people are more likely to develop a vitreous separation earlier or to develop a retinal tear or detachment. The main factors are age past 50, significant nearsightedness, a previous retinal tear or detachment in either eye, a family history of retinal detachment, previous cataract or other eye surgery, previous serious eye injury, and diabetic eye disease; the National Eye Institute lists most of these as risk factors for retinal detachment. If any of these applies to you, treat any new flash or floater as a reason to get checked promptly, even if it seems mild.

Normal Separation or Retinal Tear: Why an Exam Matters

From the outside, a harmless separation and a retinal tear can look the same, so an eye doctor needs to look at the retina to tell them apart. Once an exam shows no tear, the symptoms of a typical vitreous separation often become less noticeable over time, but new or worsening symptoms still need a repeat exam. Flashes often become less frequent over days to weeks, although some people see them on and off for months, and floaters may stay noticeable for months or longer while becoming less bothersome as your brain adapts and the debris drifts out of your direct line of sight. A small number of floaters that stays about the same after an exam has ruled out a retinal tear is often consistent with this normal course.
Sudden new flashes or a sudden increase in floaters need an urgent eye examination right away, because a retinal tear can look the same at first. Features that raise the concern are a sudden shower of many new floaters arriving at once, sometimes described as a swarm of gnats or a burst of soot, and flashes that are frequent, bright, or getting more frequent. The American Academy of Ophthalmology advises calling an ophthalmologist immediately for flashing lights that appear all of a sudden or many new floaters at once, and the National Eye Institute advises going to your eye doctor or the emergency room right away. Contact an ophthalmologist or urgent eye-care service first; if you cannot get a prompt eye evaluation, seek emergency care. A gray shadow or curtain that creeps in from one side of your vision, a blurry area in your side or central vision, or a sudden drop in vision is more urgent still and needs emergency care right away, as described in the box below.
Sudden loss of vision in one eye, on its own or together with face drooping, arm or leg weakness, slurred speech, or sudden confusion, is a different problem from a floater or a tear. It can be caused by several serious eye or vascular problems and requires emergency evaluation, particularly when neurological symptoms are present, which is why it belongs in the emergency list below rather than the see-a-doctor-soon list. Flashes, floaters, or any change in vision that start right after a direct blow to the eye, or after a significant head injury, also belong in the emergency list, since trauma can cause bleeding, a retinal tear, or other eye injury that is not visible from your symptoms alone. After a minor bump to the head or face, without vision loss, severe eye pain, bleeding, vomiting, confusion, or fainting, an urgent eye examination is still appropriate. A chemical splash is a separate eye emergency, not a cause of flashes or floaters: MedlinePlus advises flushing the eye right away with a gentle stream of cool tap water or saline for at least 15 minutes and getting medical help without delay.

What Happens During the Eye Exam

An eye doctor evaluating new flashes and floaters will dilate your pupils with drops and examine the retina, including the outer edges where tears often occur, using a bright light and a special lens. The National Eye Institute describes a dilated exam as simple and painless. Your vision may be temporarily blurry and sensitive to light afterward, and the National Eye Institute suggests asking a friend or family member to drive you home.
If the exam is normal, treatment is usually not needed, though your doctor may recommend a follow-up exam, since a tear can develop after the first exam in a small number of cases. If a tear is found before the retina has detached, it can usually be sealed in the eye doctor's office with a laser or a freezing probe, which helps keep fluid from getting underneath the retina. A retinal detachment usually requires urgent surgical evaluation and treatment. The timing and type of treatment depend on how much of the retina has detached and what type of detachment it is.

What to Do While You Wait for Your Appointment

No home method has been shown to make an existing floater disappear faster, and eye drops, supplements, or eye exercises are not proven to reverse a vitreous change that has already happened. What matters is watching for change. Note whether the number of floaters is climbing, whether flashes are becoming more frequent, and whether any shadow at the edge of your vision is spreading. Try not to rub your eyes, since that can irritate them and does not help the symptoms. Do not drive yourself if your vision is significantly affected or if you have been given dilating drops. If symptoms worsen while you are waiting for an appointment, seek urgent eye care rather than waiting for the scheduled visit; a curtain or shadow belongs in the emergency tier described below.

When to Seek Medical Care

When to Seek Urgent or Emergency Care

Flashes and floaters are often caused by an age-related separation of the gel inside your eye, but the same symptoms can also signal a retinal tear or detachment, which can threaten your vision if it is not evaluated and treated promptly. This guidance is in addition to, not a replacement for, the general disclaimer above.

Emergency, call 911 or go to the emergency room immediately if:

  • A gray shadow or curtain moves across part of your vision and stays, or a blurry area appears in your side or central vision, especially if it is getting bigger
  • You lose vision suddenly in one eye, even briefly, like someone pulled a shade down, or you notice a sudden, marked drop in your vision, especially with new flashes or floaters
  • Flashes or vision loss happen along with face drooping, arm or leg weakness, slurred speech, or sudden confusion, which can be signs of a stroke
  • Flashes, floaters, or vision changes started right after a direct blow to the eye or a significant head injury, or after any bump to the head followed by vision loss, severe eye pain, bleeding, vomiting, confusion, or fainting
  • A chemical has splashed into your eye: flush it with cool running water or saline for at least 15 minutes while you get emergency medical help

See a doctor soon (same-day or next available appointment) if:

  • You notice sudden new flashes of light or a sudden increase in floaters, which needs an urgent eye exam right away, not the next available appointment (contact an ophthalmologist or urgent eye-care service, and seek emergency care if you cannot get a prompt eye evaluation)
  • You see a sudden shower of many new floaters, like a burst of soot or a swarm of gnats, or flashes that are frequent, bright, or getting more frequent, which also needs an urgent eye exam right away
  • You have risk factors for retinal problems, such as significant nearsightedness, a family history of retinal detachment, or a previous eye injury, and you notice any new flashes or floaters
  • Your floaters or flashes started after cataract surgery or another recent eye procedure
  • Flashes or floaters started after a minor bump to the head or face, with no vision loss, severe eye pain, bleeding, vomiting, confusion, or fainting (contact an eye doctor right away)
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Frequently Asked Questions

What do eye floaters actually look like?

Floaters usually look like small dark specks, threads, cobwebs, or faint rings that drift across your vision when you move your eyes and seem to dart away when you try to look straight at them. They are most noticeable against a plain bright background, like a white wall, blue sky, or a computer screen, and less noticeable in dim light or against a busy pattern.

Do flashes in one eye need an eye exam?

Yes. New flashes in one eye can be caused by vitreous traction and should be assessed, particularly when they are sudden or accompanied by new floaters. Migraine aura usually affects the visual field of both eyes, although people may perceive it as being on one side, and it often shimmers or spreads. Because the two can be hard to tell apart, any new flashes are worth an eye exam.

Can stress or anxiety cause floaters and flashes?

Stress or anxiety can make visual symptoms more noticeable, but new flashes or floaters should not automatically be attributed to stress. Floaters and flashes usually come from physical changes inside the eye or, for flashes, sometimes from the brain during a migraine, so an eye evaluation is the way to find out.

How long do floaters from a normal vitreous separation last?

Flashes often become less noticeable over days to weeks as the gel finishes pulling away from the retina, although some people see them on and off for months. Floaters may remain noticeable for months or longer and often become less bothersome as your brain adapts, and a few faint specks can remain permanently for some people. Any sudden change during that time deserves a repeat eye exam.

Is it normal to have some floaters my whole life?

Yes, having a small number of floaters is common, especially as you get older and in people who are nearsighted, and many people simply stop noticing ones they have had for years. What deserves an eye exam is a sudden new floater, a sudden increase in how many you see, or floaters that show up alongside flashes of light, since those changes can point to a retinal problem rather than routine aging.

Can flashes of light be an early sign of a stroke?

Brief flashes off to the side of your vision are more often related to the eye than to the brain, but any new flashes still deserve an eye exam. Sudden vision loss or flashes that occur together with face drooping, arm or leg weakness, slurred speech, or sudden confusion are different, and that combination can signal a stroke, which needs a 911 call and emergency care right away. The CDC lists sudden trouble seeing among the signs of stroke.

Do all flashes of light mean I am having a migraine?

No. Migraine aura flashes often build gradually, spread across your vision, usually involve the visual field of both eyes, and last up to an hour, sometimes followed by a headache and sometimes not. Flashes from a vitreous separation or retinal tear are often brief, appear off to the side in one eye, and are not linked to head pain. The pattern is only a guide, so a first-ever aura or any new flashes still deserve an eye exam.

Should I go to the emergency room for new flashes or floaters if I cannot reach an eye doctor?

Contact an ophthalmologist or urgent eye-care service right away and say that you have sudden new flashes or floaters. If you cannot get a prompt eye evaluation, seek emergency care, ideally at an emergency room that can arrange an ophthalmology evaluation, since a delayed retinal tear can progress to a detachment. Go to the emergency room without waiting if you see a curtain or shadow, lose vision suddenly, or have signs of a stroke.

Sources

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