Visual snow: what we know about this syndrome

People who have it describe it almost always in the same way: like looking at the world through an old, badly tuned television. A continuous shower of minuscule, flickering dots across the whole visual field, on the sky as on the wall at home, which can last for years².

This is visual snow, today regarded as a disorder in the way the brain processes images¹. It is little known and often not recognised⁴, also because it is subjective: only the person who has it sees it, and even many professionals find it hard to identify⁸. In recent years research has taken more and more interest in it, but many questions remain open.

In this article

1. What visual snow is: the symptoms
2. How common it is
3. Visual snow and migraine: relatives, not twins
4. What happens in the brain
5. The treatments studied
6. Frequently asked questions
7. Sources

What visual snow is: the symptoms

The symptom that gives the syndrome its name is countless, flickering dots across the whole visual field, similar to the ‘snow’ of an untuned television, often present all the time². When the snow is on its own it is called visual snow; when it comes with other visual disturbances, visual snow syndrome¹. The associated disturbances most often described are^3,6:

• palinopsia, images that stay or repeat after you have looked away;
• a more intense perception of entoptic phenomena, that is, of what lies inside the eye itself, such as floaters;
• worse night vision;
• photophobia, that is, discomfort in light.

A 2021 systematic review also found an association with other disturbances of perception and mood and with cognitive difficulties³. Among the conditions that occur most often together with visual snow are migraine with aura and tinnitus, the whistling or buzzing in the ears⁷. The criteria for diagnosis, presented in a 2015 review², now appear in the appendix to the international classification of headache disorders⁷.

How common it is

We do not know precisely. The 2021 review reports that up to 2.2% of the population might be affected³, while another systematic review, from 2022, found only one study devoted to how common it is⁷. It can appear from childhood to old age, it is more frequent in young people and it shows no differences between men and women⁴.

These are figures to take with caution. One of the greatest difficulties, a 2020 review points out, is that visual snow is subjective and there are no objective measures to quantify it, which are indispensable also for testing treatments¹.

Visual snow and migraine: relatives, not twins

The link with migraine is close: among people with visual snow migraine is much more frequent than in the general population, and those who have both conditions have more intense symptoms⁴. For years visual snow was classified among the persistent visual phenomena of migraine².

The most recent research, however, describes it as a disorder in its own right. A 2025 review, arising from a debate among specialists, re-examined clinical, imaging and electrophysiological studies⁵. Unlike aura, visual snow is persistent, does not change with the migraine cycle and does not respond to the medicines that work against migraine⁵. The similarities, such as how often the two conditions occur together, would rather be the sign of a common predisposition to increased excitability of the cerebral cortex⁵. We described aura in Migraine with aura.

What happens in the brain

One of the first clues came from a study that measured the metabolic activity of the brain: in people with visual snow an area of the visual cortex, the lingual gyrus, consumed more energy than in controls². For the authors it was proof that the disorder, though subjective, has a biological basis².

Since then studies have multiplied. Electrical recordings have shown an excessive response of the visual areas, and MRI images have found differences in the fine structure and connections of several areas of the cortex and the thalamus, a relay station for sensory signals⁶. For this reason many researchers now regard it as a disorder of a network^3,6.

A 2018 review brings visual snow closer to other disorders in which the brain seems to process sensations badly, such as tinnitus and a type of chronic dizziness⁹. But the imaging results are not found in everyone and are sometimes contradictory⁸, and the 2022 systematic review went so far as to write that the data are few and not solid enough to regard the syndrome as a medical entity in its own right⁷. The debate, in short, is open.

The treatments studied

Today there is no established treatment^3,4. A retrospective study, that is, one based on clinical records, suggests a possible benefit of an antiepileptic drug in a minority of people, with low-level evidence¹; according to another review, the same drug can also worsen the symptoms⁸. Some antidepressants have been associated with a worsening or the appearance of the visual disturbances⁶, and alcohol, drugs and some medicines can worsen or trigger visual snow⁸. A 2022 systematic review found, on treatments, only descriptions of single cases⁷.

Among the non-drug approaches under study are cognitive therapy based on mindfulness, coloured filters, adaptation to ‘visual noise’ and visual rehabilitation programmes⁶. According to a 2025 review, so far coloured filters and eye movement training seem to give the best results¹⁰. But the level of evidence remains low, and larger studies with objective measures are needed⁶.

Frequently asked questions

Is visual snow dangerous for sight?

Reviews describe it as a disorder in the way the brain processes images, not as a disease of the eye¹. It can, however, weigh heavily on quality of life and last for years³.

Visual snow or floaters: what is the difference?

Floaters are shadows of small clumps in the gel that fills the eye. Visual snow, by contrast, is a continuous shower of dots across the whole visual field². People with the syndrome, however, often notice floaters more as well³. We discuss them in Floaters.

Is visual snow linked to migraine?

The two conditions often occur together, and those who have both have more intense symptoms⁴. The most recent research indicates, however, that they are distinct disorders, perhaps with a common predisposition⁵.

Is there a cure for visual snow?

Not yet. Studies on medicines are few and the results weak, and some medicines can worsen the symptoms^6,8. Coloured filters and rehabilitation approaches are under study, with evidence still at a low level^6,10.

Until a few years ago, people who saw the snow had few words to describe it. Today the syndrome has a name, criteria and a series of studies that point to a basis in the brain^2,3. What is missing is objective measures and larger studies, the conditions for reaching verified treatments^1,6.