Visual snow
Like an old television that never finishes tuning in.
The static flickers quickly. It stops flickering if your device is set to reduce motion. If flickering light triggers seizures or migraines for you, keep the dial at None.
Try it
Which bus is pulling in, and is it safe to cross yet?
The 84 to Riverside. The signal says wait: the top light is red.
What's happening
Visual snow syndrome fills the whole field of vision with tiny flickering dots, day and night, in both eyes. It is thought to come from overexcited visual areas in the brain rather than the eyes, which look healthy on examination. Many people also see after-images, extra floaters and trouble at night.
This simulation is for understanding and empathy. It is not a diagnosis and doesn't replace an eye examination.
What you might notice
Static everywhere
Fine flickering dots over everything, most obvious on plain surfaces and in the dark.
After-images
A bright object leaves a ghost image after you look away.
Night is harder
Dim scenes look grainy, and night driving gets difficult.
Eyes look normal
Standard eye tests are usually normal, which can make it hard to be believed.
Where it gets hard
- Reading on screens and plain backgrounds.
- Night driving and dim rooms.
- Concentration and fatigue at work.
- Being believed, because the eyes look healthy.
Often caused by
Conditions commonly linked to this pattern.
- Visual snow syndrome, often starting in young adults
- Often found alongside migraine, especially migraine with aura
- Tinnitus is common in people who have it
- Rarely, some recreational drugs
Treatment and support
There is no cure yet, and research is active. Some people are helped by certain migraine and epilepsy medicines, tinted lenses (often in the blue-yellow range) or treating accompanying migraine. A neurologist or neuro-ophthalmologist can rule out other causes first.
Looking for research you could join? Search ClinicalTrials.gov or the EU Clinical Trials register.
How to help someone with sight loss
- Say who you are when you approach, and tell them when you leave.
- Offer your arm rather than pushing or pulling, and mention steps and kerbs.
- Use large, high-contrast print and good light, and read labels and doses aloud if asked.
- Don't move their things without saying: a moved cup or key is a lost one.
Get checked the same day if
The static starts suddenly, affects only one eye, or comes with vision loss, a curtain over your view, weakness or a severe headache.
If it's sudden or comes with other symptoms, go to an emergency department.
Where to learn more
- Visual Snow Initiative
Patient information and research news on visual snow syndrome.
- The Migraine Trust
UK charity with guides on migraine with aura, treatment and living with migraine.
- National Eye Institute
Plain-language information on eye conditions.