Investigating What Sets Visual Snow Syndrome Apart from Migraines

Researchers estimate that approximately 1-2% of the population sees the world through a layer of static — similar to the visual flicker of an analog television set.

Until about a decade ago, visual snow syndrome (VSS) was thought to be a symptom of migraine, but evolving research shows that it is its own neurological disorder. However, researchers aren’t yet sure what causes it or how to treat it.

In addition to visual static, people with VSS commonly experience light sensitivity, floaters in their vision, difficulty seeing at night, tinnitus, seeing afterimages, and flashes of light. A history of migraine and migraine aura is closely associated with VSS.

“It can be a very challenging condition to live with,” says neuro-ophthalmologist Victoria Pelak, MD, professor of neurology and ophthalmology at the University of Colorado Anschutz School of Medicine. “I often hear from patients that the symptoms are difficult to get used to. It’s not just a matter of psychological adjustment – this probably has to do with how the brain functions and that it’s hard tune out these symptoms and concentrate on what’s in front of you.”

Because VSS is relatively new as an official syndrome, there are plenty of big questions about what sets it apart from migraine, what’s happening in the brain that triggers VSS, and what can be done to alleviate symptoms that often interfere with everyday life.

We asked Pelak, whose work is at the forefront of VSS research and determining how to measure whether a treatment is working, about what’s next for investigating this condition and what can make it a challenging endeavor.

What is known about what causes VSS and how do you treat it?

It’s not clear what triggers visual snow syndrome and we don’t have a lot of insight into the best ways to treat it. We often say there is no treatment, but there are things that people can do to improve their quality of life.

We have not found that people develop blindness or a brain disease from VSS, so we know it may be part of the human brain changes that occur throughout life since this condition can happen at any time in life. It may be a wiring or a network change in the brain.

We also don’t understand why it doesn’t end or why it doesn’t happen in 98% of people. It can be present in children, and it can come on in late life, and it can be very jarring at onset, so most people, except for some young children, usually remember the day that it first started happening.

Now that visual snow syndrome has been classified as a disorder separate from migraine, what does that mean for research?

The first step in trying to understand a disorder or a syndrome is really understanding the relationships it has to factors such as age, sex, other medical disorders, family history, and others. One of those medical disorders that popped up in association to VSS was migraine.

When you see strong relationships like migraine and visual snow, but not everybody with visual snow syndrome experiences migraines, then you know that there must be some other factors involved. By separating these two disorders, you can better understand the disease, because really, it's an association, but it may not be a cause.

You’ve developed the Colorado Visual Snow Syndrome Survey. How does that lend itself to the future of VSS research?

First, I should say that developing the diagnostic criteria for VSS in 2018 was a big steppingstone in defining visual snow into a syndrome. That diagnosis becomes important to study the syndrome, because if you have various research studies with different people that don't all share the same syndrome, then you may be studying completely different and separate conditions.

The next step from that is developing measurements that will be used to decide if a treatment works. I initially created the Colorado Visual Snow Symptom Survey (CVSS) and, along with our research team, assessed whether it was reliable in measuring reported symptoms. We found that that reliability upon remeasurement was not high enough for clinical trials. I rewrote the survey, and worked with collaborators to refine it to improve reliability. We published survey results of people with VSS and those without VSS using the new survey, called the CVSS 2.0, which helped to make progress toward validating the new survey.

Overall, the survey assesses the presence of symptoms and their intensity, severity, and impact on quality of life. We’ve found that it can differentiate participants with VSS and healthy controls, so that gives it good potential for measuring patient-reported outcomes in treatment trials.

What are the big questions ahead of researchers for VSS right now?

There’s a lot of interest in clinical trials for therapies to treat people with VSS. I’m open to all the results from these investigations, but there is a question of whether there is enough data to say we have valid outcome markers that tell us whether a treatment is working. To do that, we need to validate any marker that’s being used to say whether a treatment is working and that requires a lot of work.

It's excellent to move forward to looking and piloting treatments, but until we have valid and reliable markers that tell us whether symptoms are changing for the better, not for the worse, or not changing at all, it's going to be very, very difficult for us to be confident in any study that looks at treatment.

So, developing this survey is an early step toward additional research that may become useful in searching for treatments because it allows for the most accurate data possible?

That’s correct. You always need outcome measures to tell you whether a treatment works, and those outcome measures should be valid and reliable.