Visual snow syndrome means seeing many tiny flickering dots, like snow or static, across your entire field of vision. For most people the snow is always there, in both eyes. The cause is unknown but likely involves how the brain processes vision, and it can come with afterimages, light sensitivity, poor night vision, migraines and ringing in the ears. It is diagnosed once the symptoms have lasted more than three months, eye exams are normal and other causes have been ruled out. There is no cure; some people improve with certain medicines, and tinted lenses are among the options tried. New flashes of light, a sudden shower of new floaters or a shadow over your vision are a different problem: call us right away at 310-828-2010, or go to an emergency room when we're closed.
Key takeaways
- Visual snow likely involves how the brain processes vision, though the exact cause is unknown, and for most people the static is always there in both eyes.
- A diagnosis needs symptoms lasting more than three months, normal eye exams and other causes ruled out, so an eye exam comes first.
- No cure exists yet, though some people improve with medicines such as migraine preventives or antidepressants, and tinted contact lenses are another option.
- New flashes, a sudden shower of new floaters or a shadow over your vision mean calling us right away for a same-day exam, or an emergency room when we're closed.
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What is visual snow syndrome?
Visual snow syndrome affects the way visual information is processed by the brain and eyes. Its main symptom is the snow itself: many flickering tiny dots, like snow or static, that fill the entire visual field.
For most people with the syndrome, the snow is always present and occurs in both eyes, and because it never switches off, it can lower a person's quality of life.
02
What other symptoms come with visual snow?
The snow can come with other symptoms. GARD lists:
- Floaters: blobs of varying size and shape that drift through your vision
- Afterimages, called palinopsia: still seeing an image after it has left your line of sight
- Light sensitivity (photophobia)
- Trouble seeing at night or in the dark (nyctalopia)
- Migraines and other headaches
- Ringing in the ears (tinnitus)
Many people with visual snow syndrome also have anxiety or depression, which GARD lists among its common symptoms, and GARD advises talking with a doctor about the right treatment for those symptoms.
03
What causes visual snow?
The cause is still unknown. GARD says it is likely to involve how the brain processes vision. Some researchers suspect the symptoms come from nerve cells in the brain responding too strongly to visual signals.
Most people with the syndrome have normal eye exams, and brain scans such as CT and MRI are normal too.
04
Is it visual snow, a migraine aura or floaters?
How the symptom behaves over time helps tell these apart.
| Feature | Visual snow | Migraine aura | Floaters |
|---|---|---|---|
| What you see | Many tiny flickering dots, like static, over the whole visual field | Dots, zigzags, sparks or flashing lights | Small dark spots, threads, squiggly lines or cobwebs |
| How it behaves | Always there for most people | Starts about 10 minutes to an hour before a migraine and usually lasts no more than an hour | Moves as your eyes move and seems to drift away when you look at it |
| Where it comes from | Likely the way the brain processes vision | Part of a migraine episode, sometimes with no headache | Usually normal changes in the gel inside the eye |
A migraine aura usually affects vision, with dots, zigzags or sparks. It appears about 10 minutes to an hour before the headache and usually lasts no more than an hour. Some people have a migraine episode with vision symptoms and no headache at all.
Floaters are small dark shapes that float across your vision, and they usually happen because of normal changes in the vitreous, the gel-like fluid that fills the eye. Floaters are also on GARD's list of symptoms that come with visual snow, so having them doesn't rule it out. Our page on floaters and flashes explains which floaters are urgent.
05
How is visual snow syndrome diagnosed?
Visual snow syndrome is diagnosed based on the symptoms. Doctors make the diagnosis when the symptoms have lasted more than three months, eye exams are normal and other possible causes have been ruled out.
That makes a thorough eye exam the first step. New flashes and floaters can come from a retinal tear or detachment, and dilating the pupils lets the eye doctor check the inner parts of the eye for problems like that.
If your eyes are healthy, GARD's page on visual snow notes that a neuro-ophthalmologist, a specialist in vision problems that come from the nervous system, may be helpful in diagnosing rare conditions that affect vision and the brain.
Before your visit, it helps to note:
- When the snow started, and whether it has been there for more than three months
- Whether it seems to be in both eyes
- Any other symptoms from the list above, such as afterimages, light sensitivity, trouble seeing at night or ringing in the ears
- Whether you get migraines or other headaches
06
Can visual snow syndrome be treated?
There is currently no cure, and no treatment is known to work for everyone with visual snow syndrome. Studies proving that the treatments work and are safe have not been completed.
Some people have improved with certain medicines, such as migraine preventives, antidepressants, anticonvulsants or over-the-counter pain relievers. GARD also lists tinted (colorimetric) contact lenses among the treatment options.
Treatment usually doesn't relieve the symptoms completely, but in many cases easing them improves quality of life. Talk with your doctor about the benefits and risks of any treatment before you start it.
If light sensitivity is a large part of your symptoms, tell us at your exam so we can talk through the options.
07
When are new visual symptoms an emergency?
Static that has looked the same for months calls for a routine exam. New symptoms are different. Call 911 for any of these:
- Sudden loss of vision in one or both eyes, even if it comes back
- Sudden double vision
- Double vision or a droopy eyelid with a pupil that looks different, eye pain or a severe headache
- Any change in vision with face drooping, arm weakness or trouble speaking
The American Stroke Association lists sudden changes in vision, such as blurred vision, double vision or loss of sight in one or both eyes, among the warning signs of a stroke. Call 911 for the signs above even if they go away, and check the time so you know when the first symptoms appeared. Sudden blur on its own that doesn't clear needs an emergency room; if it clears right away, call us and come in for an exam.
Call our office right away for a same-day exam, or go to an emergency room when we're closed, if you see new flashes of light, a sudden shower of new floaters, or a dark shadow or curtain over part of your vision. These can be signs of a retinal tear or detachment, which can be a medical emergency.
Our office hours are Monday 10 to 5 and Tuesday through Friday 8 to 5. When we're open, call 310-828-2010 first so we can triage you; our urgent eye care page explains how same-day visits work.
08
How we check visual snow symptoms at Cohenmehr Optometry
Static that has looked the same for months is checked at a comprehensive eye exam, where our eye doctors in Los Angeles examine the retina by dilation or wide-field imaging. An urgent visit for new visual symptoms can include a dilated retinal exam, retinal photography and OCT imaging, a scan of the retina and optic nerve, with visual field testing when it's needed.
Those images become a baseline, so if your symptoms ever change, we can compare the new scans against the old ones.
If we find a retinal problem, the referral to a retina specialist and your records go out the same day. If your eyes are healthy, we'll talk about next steps for the brain side of visual snow, including whether to see a neuro-ophthalmologist. Our eye symptom guide sorts other visual complaints by how urgent they are.
09
Questions patients ask
Why am I seeing sparkles?
Sparkles can come from a few different places, and timing helps sort them out. A migraine aura can bring dots, zigzags or sparks that usually last no more than an hour. New flashes of light, or a sudden shower of new floaters, can mean a retinal tear or detachment: call an eye doctor right away, or go to an emergency room if the office is closed. Call 911 if sparkles come with face drooping, arm weakness or trouble speaking. Fine static that is always there fits visual snow.
What is a dilated eye exam?
It's an exam in which drops widen your pupils so the doctor can check the inner parts of your eye for problems. Dilating the pupil lets more light into the eye, and the exam is simple and painless. For a few hours afterward your vision may be blurry and you may be sensitive to light, so bring sunglasses and ask someone to drive you home. NEI recommends a dilated exam to catch eye diseases early, when they're easier to treat and before they cause vision loss.
Can screen time make visual snow worse?
It can. Visual snow can get worse when the eyes are tired, such as after looking at a computer screen for a long time, and during times of stress. Breaks won't cure it, but knowing your own triggers can help you plan around them. If screens also leave your eyes tired, dry or strained, have that checked separately; our page on computer vision syndrome covers the usual causes.
Does visual snow go away?
Usually not on its own. GARD notes that the symptoms of visual snow syndrome do not usually change over time, although some people notice them improve, with or without treatment, and others notice them get worse. There is no cure, so treatment aims to ease the symptoms. New flashes, a shower of new floaters or a shadow over your vision are a separate problem: call an eye doctor right away, or go to an emergency room if the office is closed.
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Sources
- GARD (NIH): Visual snow syndrome
- GARD (NIH), in Spanish: Síndrome de la nieve visual
- National Institute of Neurological Disorders and Stroke: Migraine
- National Eye Institute: Floaters
- National Eye Institute: Get a dilated eye exam
- American Stroke Association: Stroke symptoms
Written by
Dr. Kevin Cohenmehr, OD
Medical eye care: glaucoma, diabetic eye exams, macular degeneration and eye infections, plus vision therapy for children. A graduate of UCLA and SUNY College of Optometry.
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