frequently asked questions

> Frequently Asked Questions

Visual Snow Syndrome (VSS) is a neurological condition that impacts an individual’s vision, hearing, cognition, sensory processing, and quality of life. The primary symptom of VSS is seeing visual snow, which can be described as seeing static, flickering dots, and flashing lights 24/7 (with your eyes both open and closed). VSS also entails a variety of other debilitating visual and non-visual symptoms. It is not a structural issue with the eyes.

VSS is a processing condition that originates in the brain, not the eyes. This explains why eye tests typically come back “normal” for people with VSS and why it is so difficult for physicians to diagnose, especially if they are unfamiliar with the condition.

The exact cause of VSS is still unknown. Research suggests it is related to changes in the visual processing centers of the brain, as well as alterations in the neural signals between the eyes and the brain. The origin of VSS has also been linked to hyperactivity in the visual cortex of the brain. 

In a recent brain scan study supported by the Visual Snow Initiative, researchers discovered a possible biological basis for Visual Snow Syndrome.

Using a combination of information from positron emission tomography (PET) imaging information on the distribution of different chemical receptors in the brain and functional Magnetic Resonance Imaging (fMRI), researchers found that the patterns of activity in two brain chemical systems – glutamate and serotonin – are different in people with Visual Snow Syndrome compared to those without the condition.

“There was less synchronised activity (or functional connectivity) in the glutamate networks in the anterior cingulate cortex (ACC) in those with VCC compared to healthy controls. The ACC is a hub for thinking and top-down control over sensory inputs and the different pattern of activity could represent an interruption in the filtering and integration of visual information. 

Analysis also showed that VSS patients had reduced functional connectivity in the serotonin networks of the visual cortex, insula, temporal pole and orbitofrontal areas of the brains compared to healthy controls. This reduced connectivity in serotonin networks was also seen in migraine patients with aura suggesting a biological link between VSS and aura. The findings suggest that serotonin activity in VSS patients may be influencing the integration of complex sensory information.” — National Institute for Health and Care Research (NIHR) Maudsley Biomedical Research Centre

Research into the causes of VSS is ongoing and increasing day by day, so it is likely that we will learn more about its causes in the coming years.

VSS is diagnosed based on a patient’s symptoms and based on a thorough clinical evaluation, including a comprehensive medical history and a comprehensive eye exam to rule out other eye-related conditions. In some cases, an MRI or EEG may be ordered to rule out other neurological conditions. Neuro-ophthalmologists and neurologists are best equipped to diagnose VSS. If you suspect you may have VSS, you can refer your doctor to our Diagnostic Criteria.

It can often be difficult to find medical professionals who understand or specialize in VSS. The VSI has a list of physicians from around the world with knowledge of VSS that can help with diagnosis and treatment options. For more information, please see our Physicians & Specialists Directory.


The most common symptoms of VSS include visual snow (seeing static), photophobia (sensitivity to light), tinnitus (ringing in the ears), migraines (with or without aura), and visual disturbances, such as enhanced entoptic phenomena, halos, palinopsia, and more.

For a more comprehensive list of VSS’s visual and non-visual symptoms, please see our Diagnostic Criteria.

Visual Snow Syndrome (VSS) is a neurological disorder. VSS refers to the syndrome itself, which encompasses a series of visual and non-visual symptoms. Visual Snow (VS) is one of these symptoms. The main symptom of VSS, Visual Snow refers to seeing constant static, or dynamic, continuous tiny dots across the entire visual field persisting for more than three months.

HPPD is typically associated with prior use of hallucinogenic substances and is often triggered or exacerbated by substance use. VSS can occur spontaneously without any history of substance use.

Patients have reported that their VSS symptoms worsen during periods of heightened physical or mental stress. These symptoms typically stabilize or decrease in severity once stress levels have been reduced.

VSS can affect anyone from any age group, country, or ethnicity. According to research, it is most commonly reported in young adults with an average age of 29.

Currently, there is no known cure for VSS. However, some patients have reported improvements in their symptoms with various treatments, coping strategies, and lifestyle changes.

According to patients, the following have been reported helpful for their symptoms:

To determine what may work best for you based on your specific symptoms and medical history, it is important to consult your doctor or a qualified health provider.

For more information, please visit the following page: Managing VSS

Neuro-Optometric Rehabilitation Therapy (NORT), neurovision therapy, and the Tsang/Shidlofsky Protocol or Study are all different names that essentially refer to same type of treatment for Visual Snow Syndrome (VSS). 
Medical professionals and researchers may prefer to use a specific treatment name for academic, clinical, or diagnostic purposes within their studies and in-practice. Patients who have been treated or are being currently treated typically refer to the treatment using the same name their physician does. 
Most recently, when referring to the aforementioned treatment, we primarily use the name, Neuro Optometric Rehabilitation Therapy (NORT). 
NORT refers to a non-invasive drug-free treatment for neuro-visual symptoms. It aims to rehabilitate the neuro-visual system, alleviate symptoms, and improve quality of life for patients. NORT has already been used by medical professionals worldwide for a variety of conditions. It is now being utilized and is recognized as an effective treatment for VSS. 
Neurovision therapy is an alternate name for NORT, preferred by some physicians and patients.
The Tsang/Shidlofsky Protocol or Study refers to Dr. Terry Tsang and Dr. Charles Shidlofsky’s NORT protocol that has been specifically customized for VSS patients based on their medical history and the specific set of VSS symptoms they may experience (as well as the intensity of these symptoms).

There are several online support groups for people with VSS. Social media is also an excellent way to connect, share experiences, and receive support from others who understand the condition.

While VSS is not considered a common condition, it is also not rare. It is estimated that up to 2-3% of the population may experience some form of VSS symptoms. Additionally, many people born with VSS may be unaware that they have a neurological condition, because they assume that others see the world as they do. So the actual number of cases could be higher worldwide.

Yes, VSS can significantly impact a person’s quality of life. Many people with VSS are sensitive to visual and auditory stimuli, making them more prone to “sensory overload”. For some, their VSS symptoms make daily tasks, such as driving or working, very difficult. Others face challenges when it comes to school, social activities, reading, enjoying nature, and technological devices. VSS can also lead to anxiety, depression, and other emotional difficulties.

But not every case of VSS is the same.  For more information regarding how/why VSS affects each person differently, please visit the page, Understanding VSS. While having VSS can affect a person’s life, the degree of impact varies from person-to-person depending on several factors. Some examples include:

  • How long the person has experienced VSS symptoms 
  • Which specific VSS symptoms they experience 
  • The severity of their symptoms
  • Which triggering factors worsen their VSS symptoms
  • Access to a physician or healthcare provider with knowledge of VSS who can help them
  • Lifestyle
  • Accommodations available to them, especially at work or school
  • Degree of support 
  • Personality
  • Medical history

No, VSS does not cause blindness nor is it degenerative. However, it can cause significant visual disturbances and impact a person’s quality of life.

It can often be difficult to find medical professionals who understand and specialize in VSS. The VSI has a list of physicians from around the world with knowledge of VSS that can help with diagnosis and treatment options. For more information, please see our Physician & Specialists Directory.

If there is no physician listed in your location, you can start by speaking with a neuro-ophthalmologist, neurologist, or ophthalmologist in your area regarding your symptoms. It is important to show them our Diagnostic Criteria and provide as much information on VSS as possible, as they may be unaware of this condition.

Explaining VSS to others can be challenging, as it is a complex and often misunderstood condition. We try our best to explain VSS in an understandable way on both our website and social media, which can be helpful resources. You may want to share information, educational materials, and/or multimedia content about VSS with others to help them better understand what you are going through. Describing visual phenomena with words may be difficult, so showing people photos or videos that accurately depict your symptoms can help them understand further. You may also want to share personal stories from other Visual Snow Warriors that resonate with you. It helps to remain considerate and patient throughout the process, especially if someone has never heard of VSS before.

While the exact cause of VSS is unknown, there have been some reports of VSS running in families, suggesting a potential genetic component. However, more research is needed to fully understand the hereditary aspects of VSS.

Yes, research on VSS is ongoing, and scientists are working to better understand the causes, mechanisms, and management of VSS. This may include studies on pathophysiology, potential treatments, underlying brain mechanisms, and associated conditions.

For more information on clinical trials involving Visual Snow, please visit or ICH GCP.

Oftentimes, due to regulations (privacy & legal protection), participants for studies must be recruited via the institution or university that the researchers are affiliated with. Patients seen by physicians & researchers in-practice or in-person are often considered favorable candidates for studies. However, there are exceptions and researchers may notify the Visual Snow community when they are seeking participants for studies. They will inform you what information they need and what specific facets of VSS they are exploring via clinical trial databases, their website, and/or social media. 

You can also reach out to VSS researchers if you would like to share information about your case that may be helpful to them. The names of many VSS researchers and physicians can be found on our website.

In addition to the databases above, we also share study participation opportunities and information related to VSI-funded/supported clinical trials and research studies via our website, newsletter, and social media.

Our website, specifically, our News & Research page, can be a valuable resource for new information regarding VSS. You can also sign up for our newsletter and follow VSI on social media to stay informed about the latest developments and explore a variety of VSS-related content. Thank you for the support.

No, the Visual Snow Initiative does not provide any medical advice or a diagnosis. The information on our website is for informational/educational purposes only and is not a substitute for professional medical advice. It is important to consult with a qualified healthcare professional for an accurate diagnosis, symptom management, and/or treatment of VSS.

You can contact the Visual Snow Initiative by visiting our website and clicking on the Contact tab. You can also reach out to us through our social media channels or email us with your inquiries or feedback. We strive to respond in a timely manner.

Yes, the Visual Snow Initiative encourages individuals to share their personal story and/or projects about VSS. If you would like to share your personal story or project about VSS, please fill out this form. Your journey can inspire others and raise awareness for VSS.

Thank you for your interest in donating to the Visual Snow Initiative. Donating to VSI is easy. You can visit our website and click on the Donate button to make a secure online, tax-deductible donation. We greatly appreciate your support in advancing research and advocacy efforts for Visual Snow Syndrome.

The Visual Snow Initiative website is for informational purposes only. The contents do not constitute medical advice; the content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. This website does not recommend or endorse any specific tests, physicians, products, procedures, opinions, or other information that may be mentioned on the Site. Reliance on any information provided by this website is solely at your own risk.

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