Visual Snow Syndrome (VSS) is a neurological condition. People with it see tiny, flickering dots across their whole field of vision all the time, much like the static on an old television (2018 review of visual snow syndrome↗). It often comes with other visual symptoms, such as afterimages and sensitivity to light (2020 study of 1,100 people↗).
Eye tests come back normal (ICHD-3 criteria↗). Brain studies point to a problem with how the brain filters what the eyes see, rather than with the eyes themselves (2021 review of brain studies↗).
The International Classification of Headache Disorders (ICHD-3)↗ defines visual snow with these criteria. All four must be met.
Those are the formal criteria. Here's what living with them is like.
Most people compare the dots to television static. They're usually dark on light backgrounds and light on dark ones, but some people see transparent, flashing or coloured dots (ICHD-3 notes↗).
In a study of 1,100 people with visual snow↗, black and white static was the most common, and the condition usually started early in life: about 40% had it for as long as they could remember. The most common extra symptoms were floaters, afterimages and sensitivity to light.
Visual snow rarely comes on its own, though.
Migraine is its most common companion. It affected 59% of people in Schankin and others' 2014 study↗, and just over half of the patients in a Dutch clinic's records of 58 patients↗. That clinic also found depression and anxiety common.
Tinnitus, a constant ringing or buzzing in the ears, is very common too. People with migraine or tinnitus tend to have more visual symptoms (Puledda and others, 2020↗).
Like migraine, visual snow is often made worse by light.
Sensitivity to light (photophobia) is one of the diagnostic criteria, and one of the most common extra symptoms.
Colour matters too. In a study of colours and visual snow↗, violet-blue light that strongly stimulates the eye's blue-sensitive cones made symptoms worse, while orange-yellow or turquoise tints eased them.
Flickering light is a known trigger of headache and migraine, and people with migraine are more likely to be bothered by it (Miller and others, 2024↗).
Why would light, colour and migraine all play a part? The answer lies in the brain.
The visual cortex, which processes what we see, is overexcitable in visual snow (Fraser, 2022↗). Brain scans also show changes in areas well beyond vision (“Structural and functional footprint of visual snow syndrome”↗), so visual snow is described as a network disorder, involving several connected parts of the brain (Klein and Schankin, 2021↗).
Brain chemistry is involved too. Puledda and others (2023)↗ found altered connections linked to glutamate, the brain's main “go” signal, and to serotonin. The serotonin changes resembled those in migraine with aura, pointing to a shared biology between the two.
The Brain Model page shows these areas in 3D and follows an image through the brain step by step.
These differences aren't necessarily fixed. Neuroplasticity is the brain's ability to rewire itself through experience and training. After a mindfulness course designed for visual symptoms, brain scans showed changes in how visual networks were connected (Wong and others, 2024↗), and the researchers suggest neuroplasticity may explain such improvements (Wong and Wingrove, 2025↗).
That idea underpins several of the treatments below.
There's no cure yet, and most treatments only partly relieve the symptoms (review of 27 studies↗). These have the most evidence so far.
Eye coordination problems, such as trouble focusing or keeping both eyes working together, are common alongside visual snow: one clinic found them in about 40–50% of its patients (2023 study of 40 patients↗). Standard eye tests often don't check for them. If you also have eye strain, double vision, or trouble focusing or reading, ask a neuro-optometrist or orthoptist to check your eye coordination. These problems are treatable, even if the snow itself remains (Ciuffreda and others, 2023↗).
Most of these findings are less than ten years old, and understanding has come a long way.
A simplified model of the parts of the brain linked to visual snow. The shapes and positions are approximate. Drag to turn it, pinch or scroll to zoom, and tap a part to learn about it.
Loading the model…
Simplified: real vision runs in parallel, with signals also flowing back, not in a neat line.
Tap a part of the model, or pick one from the list, to learn about it.
Finding found in studies of people with visual snow. Hypothesis a proposed explanation that isn't proven yet.
Building the house…
Drag to look around. Walk with the pad.Click to look around with the mouse; Esc or right-click lets go of it. Walk with WASD or the arrow keys.
Switch to Visual snow at the top to use these.
Keys: WASD or arrows to walk, E effects, C hold to close eyes, T Typical or Visual snow, 1–6 switch effects, M menu, Esc let go of the mouse.
Based on the symptoms in the ICHD-3 criteria↗ and the research on the About page. It's an approximation: everyone's visual snow looks different.
This simulator shows flickering static and bright light effects. Don't use it if you have photosensitive epilepsy or flicker makes you unwell.
Stop straight away if you feel dizzy or get a headache.
Short practices in noticing what you see, hear and feel, without reacting to it. They’re inspired by MBCT-vision, a mindfulness course adapted for visual symptoms.
Practice, not treatment. MBCT-vision is an 8-week course led by a therapist. These short practices are based on its ideas, but haven’t been tested on their own or in an app.
The tone tells you when there’s a new step, so you can close your eyes or look away from the screen between steps.
Finding In an 8-week study of 21 people↗, MBCT-vision lowered the severity of visual snow and its impact on daily life, and the improvement lasted to 20 weeks, with changes on brain scans. The study had no comparison group, so a randomised trial of MBCT-vision↗ is under way.
Finding People with visual snow find it harder to control where their attention goes (Foletta and others, 2021↗).
Hypothesis Researchers suggest that attention locking onto the symptoms may help keep them going, and that mindfulness may loosen that lock (Wong and Wingrove, 2025↗). That’s why these practices never ask you to watch your snow: if it catches your attention, you notice that and move on.
Widening attention to the edges of vision is also part of the vision therapy described on the About page.
Stop if a practice makes you feel worse, dizzy or anxious. For the full course, ask your doctor or see the trial above.
Finished
Take a moment before moving on. You can come back to a practice any time.
Visual Snow Awareness was built independently by Daniel D'Agostino↗.
The app contains no tracking: no analytics, no ads and no accounts. Your settings are saved only on your own device. (Like any website, the web host may keep standard server logs.)
That also means I can’t see how the app is used, so your feedback is the only way I learn what helps and what doesn’t. I’d really appreciate hearing from you, for example about:
For questions about your own symptoms, please see a doctor.
Tap the screen for controls
This app shows flickering static. Don't use it if you have photosensitive epilepsy or flicker makes you unwell.
Relax and look through the static. Stop straight away if you feel dizzy or get a headache.
This is an experiment, not a treatment, and it isn't medical advice.