Bodily Oddities

Visual snow

Also called: Visual snow syndrome · Static

Tiny flickering dots across the whole field of vision, like static on an old TV, present with eyes open or closed. About 2–3% of people have it. The eyes are fine. The visual part of the brain is over-active.

Brain Eyes Involuntary Involuntary
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How common

About 2–3% of people Uncommon · 1–10% Many people have had it as long as they can remember and assume everyone sees it.

Does this happen to you?

These are answers from visitors, not a study.

How it works

The snow is constant. The dots are tiny, flickering, black and white or coloured, and they cover everything you look at. They are there with eyes open and closed, in light and in the dark1. Most people with visual snow also have palinopsia, afterimages that linger too long2. Many also see stronger floaters and blue-field dots than usual, are sensitive to light, hear tinnitus, and get migraines1.

Eye tests come back normal. The problem is in how the brain processes vision. Studies show that neurons in the visual areas of the brain fire too easily. This is called hyperexcitability1. The exact cause is not known. Visual snow is not a hallucination. The brain is not inventing objects. It is more like the noise floor of the visual system, which everyone has, turned up loud enough to see.

About 2% to 3% of people have visual snow1. It often starts in childhood or the teenage years, and many people assume everyone sees the same thing until they describe it1. Doctors first defined it as a distinct syndrome in 20141.

Is it a problem?

It is not dangerous. Visual snow does not damage the eyes or the brain, and it does not lead to blindness. For many people it is mild. Knowing what it is, and finding others who have it, helps most3. Tinted glasses help some people. Medicines have been tried with mixed results, and there is no reliable treatment yet1.

See an eye doctor if you notice it for the first time, and a neurologist if the eyes are normal. Go sooner if it starts suddenly, or comes with a headache, weakness, or a new medicine. That rules out other causes. Once diagnosed, visual snow does not need emergency care.

Sources and further material

  1. Encyclopedia Visual snow syndrome Formal description of the syndrome by Schankin et al., 2014.
  2. Encyclopedia Palinopsia The lingering afterimages that often go with visual snow.
  3. Community r/visualsnow Support community.
  4. Video Visual snow simulation YouTube search.
Eyes Involuntary

Floaters

Small grey threads, dots, or cobwebs that drift across your vision and dart away when you look at them. They are shadows of tiny clumps inside the eye. They are common and usually harmless.

About 70% of people, at some point
Eyes Perception

Palinopsia

An image that keeps appearing after the thing you saw is gone. Brief trails behind moving objects are common and harmless. Copies that persist or return minutes later need a doctor.

Brief trailing is common. Persistent forms are rare.
Brain Involuntary

Migraine aura

A shimmering zigzag or C-shaped patch of light that grows across your vision over 5 to 60 minutes and then fades. It can come before a migraine headache or, in some people, with no headache at all.

About 3% of people
Ears Involuntary

Tinnitus

A ringing, hissing, buzzing, or roaring sound with no source outside your head. Between 15% and 20% of people have it. It is mostly the hearing system filling in for damaged or tired inner-ear cells.

About 15–20% of people