It can cause television-like static or trails of light in the vision, but the disorder baffles the experts – so much so that a handful of doctors and patients are fighting to prove it really exists

Visual snow is a poetic name for a strange visual anomaly. Those affected find their vision is busied by a kind of snow, or television-like static, which is often accompanied by small, moving lights or afterimages that linger like a visual hangover. It can be something they have always experienced, or it can happen suddenly, and it is not something from which you can experience relief. Indeed, it can become more pronounced when you close your eyes. There is no cure, and very little is understood about its cause; current research shows the eyes themselves are normal, and it is not known which part of the brain is involved.

Even Googling the phrase returns few results. There is no NHS page dedicated to the condition (and there are NHS pages dedicated to dandruff and grazes).

“There is not an NHS page for visual snow because visual snow doesn’t exist,” says Professor Peter Goadsby, one of the few experts on the condition working in the UK. An expert in migraine and a director of the Wellcome Trust’s National Institute for Health Research at King’s College London, Goadsby became interested in the condition due to an overlap in the perception of visual snow as a form of migraine aura. He recognised what he calls a “homogenous disturbance”. “It currently isn’t recognised within medicine. When I first proposed it as a condition worth researching, colleagues thought I was completely, barking crazy,” he says.

People who experience visual snow commonly describe their field of vision as like an old, out-of-tune television. Others describe images persisting after the visual stimulus has left, dragging or remaining in the field of vision as a kind of negative space (a disturbance known as palinopsia). Squiggly lines and flashes of light are also consistently reported. Impaired night vision, photosensitivity and tinnitus are more rare effects.

Some people have experienced it for as long as they can remember, but it is difficult to know how many people have always lived with it, since they may not realise it is a peculiarity. “We tend to use ourselves as a standard of normality,” Goadsby says. Indeed, he was working on a visual snow study with a doctor who, on hearing descriptions of the condition, recognised the experiences as his own. “This is a person who has been through medical school, who knows how the brain works,” says Goadsby. “But he thought that was how everyone saw. He didn’t realise he was different.”

So, working out how many people are afflicted with visual snow is a “broadly impossible question”. Also, it is a condition that can strike regardless of age. Amanda Wright, a master’s student in Copenhagen, says she has “had this strange way of seeing my whole life, and no one really listened or understood me when I tried to explain”. Her visual snow manifests as static, dragging trails of light, and, unusually, as detailed motifs, such as military scenes and a “Guatemalan marketplace”. “I think about what it might be like to see without static or lights. It must be very calm,” she says.

At least, Wright suggests, you are never bored. “You can look up to the ceiling and see a symphony of lights.” And there is relief in the fact that, “while you always have visual snow, you don’t always experience it: when absorbed in a task, you won’t have conscious awareness of it”.

There is only one charity funding research into the condition. The Eye on Vision Foundation was set up by Jennifer Ambrose, who has seen static upon closing her eyes, or in the dark, for as long as she can remember. On waking up one morning to floating clouds and spots heavily obscuring her vision, she booked an appointment with an eye doctor, discovering only that she had no retinal tears and no visible damage. Her situation didn’t improve; in fact, it got steadily worse. “I was having ghosting images, halos, glare.” She founded Eye on Vision to raise awareness and fund research.

“The medical community are more supportive now than they were 10 years ago. The response is still: ‘There is nothing we can do for you,’ but it is a fair response, because there needs to be more research.” In terms of practical advice, guidance on managing the condition varies, but includes avoiding fluorescent lighting, wearing polarised sunglasses and taking regular breaks when using a computer.

As with many health conditions for which little therapeutic support is available, there is an active online community. The Visual Snow Support Group on Facebook has more than 5,000 members, and topics of conversation range from updates on neurology appointments to exchanging dietary tips. John Kramer, 39, from Michigan in the US, administers the group. “The Facebook group is ... a place where people can come to learn about the condition, but also get support for the times when the condition causes us to reach our breaking point,” he says.

Little is known about the causes of visual snow. There are theories of links to legal and illegal drug use, auto-immune disease, Lyme disease and hallucinogen persisting perception disorder, but nothing has been proved. Goadsby’s aim, meanwhile, is simply to get the condition validated by the wider medical community. “There is so little done for these people. While many are getting on with their lives, some are completely disabled by the condition. We need to understand exactly what we’re working with. We need to clarify what is happening with people’s brains. We know it eventually stabilises. We know that you won’t lose your vision. We’ve done some brain imaging and have seen some unusual activity in the visual cortex at the back of the brain.

“It doesn’t exist,” he repeats. “I’m going to make it exist.”