What is Visual Snow Syndrome?

Visual Snow Syndrome ('VS') is a devastating neurological condition that can affect an individual’s vision, hearing, cognitive and other functioning. A landmark study published in 2014 proposed diagnostic criteria which provides the best definition of VS. According to the study, patients must have:

  • Visual snow (i.e. dynamic, continuous, tiny dots in their entire visual field) for three months, and
  • At least two of the following four categories of additional symptoms (which are explained and illustrated on the symptoms page):
    • Palinopsia (afterimages or trailing),
    • Enhanced entoptic phenomena (floaters, blue-field entoptic phenomena, self-light of the eye or spontaneous photopsia)
    • Photophobia (light sensitivity), and
    • Nyctalopia (impaired night vision).

Additionally, their symptoms must not be:

  • Consistent with a typical migraine visual aura (i.e. a migraine that produces visual symptoms), or
  • Attributable to another disorder (i.e. the patient’s eye exams produce normal results, and they have not taken any psychotropic drugs).

Most patients experience many other additional symptoms; these are also explained and illustrated on the symptoms page. VS affects a patient's vision 24/7, which means that they never have any relief from it – even when they close their eyes. Currently, there is no cure for the disease and it is yet to receive widespread recognition within the medical profession.

'I’m stuck at home. I can’t see. I can’t go anywhere. I can’t see my way around where I’m going. I can’t drive. I can’t see my friends. I can’t go to school. I can’t do anything anymore.’ – Jack Lea


Does VS get worse?

The progression of Visual Snow Syndrome varies from person to person. Sometimes the symptoms are stable and unchanging. For others, the condition gets progressively worse, either by developing more symptoms or existing ones becoming more severe.

In rare cases, symptoms may actually improve, but identifying any specific cause for the improvement is usually impossible. More commonly, as times passes patients get used to VS, creating the illusion of an improvement - this is more common where symptoms are stable rather than progressive.

Can VS cause blindness?

Visual Snow Syndrome is ‘benign’, which means that it will NOT lead to permanent blindness in the sense that you will only see blackness. Understanding this is important because patients new to VS often fear that they are going to lose their eyesight. 

However, in extremely rare cases, if the symptoms are severe enough VS may cause blindness in the legal sense.

What triggers the onset of VS?

Nobody really knows. Some people attribute the development of Visual Snow Syndrome to a specific, often stressful, event. Others blame a migraine that never disappeared, and some say that they were born with it. Evidently, there is no one single cause, and in many cases there appears to be no trigger.

What is the pathophysiology of VS?

A study in 2015 found that patients with Visual Snow Syndrome have hypermetabolism in the right lingual gyrus and left cerebellar anterior lobe of the brain. Essentially, it means that those parts of the brain are overactive. A research review on VS suggests that the lingual gyrus plays an important role in an active system in a 'normal' person's brain that suppresses the symptoms experienced by VS patients. It is believed that since the lingual gyrus is overactive in VS patients, the suppression system malfunctions and fails to filter out VS symptoms. For example, a healthy person's brain usually filters out entoptic phenomena such as floaters, but VS patients' brains fail to do this resulting in them experience excessive entoptic phenomena. It is still unclear exactly what role the cerebellum plays in VS. Other hypotheses include visual cortical hyperexcitability and thalamocortical dysrhythmia. Ultimately, even though the exact mechanism is yet to be established, the research suggests that VS is a neurological problem. So, the problem is in the brain, not in the eyes; this would explain why all eye tests come back normal for patients. Nor is VS a sign of a brain tumour, as often feared by some VS patients.

How is VS treated?

There is currently no treatment available for Visual Snow Syndrome (hence why money is desparately needed to fund research). Some patients have been prescribed medicines by their doctor, and others have tried to treat it themselves, such as by taking certain supplements (e.g. vitamins that help prevent migraines) and lifestyles changes. Unfortunately, these have all produced very little success. In cases where there has been an improvement, it cannot be confirmed whether this occurred naturally or due to a specific change/treatment. 

What impact does VS have on the lives of patients?

Visual Snow Syndrome’s impact depends on how severe the symptoms are. For some the symptoms are almost unnoticeable, causing little impact on their lives. For others, the condition is very bad and greatly impacts their lives; this is evidenced by the sad accounts of peoples' experiences with VS which you can watch on the Real Stories page. VS seems to impact patients in three main ways.

First and foremost, the symptoms themselves can be debilitating. For instance, as you can see on the Symptoms page, the visual snow can be so dense that it obscures whatever you are looking at. Another example is pattern glare making it impossible to read. Therefore, Visual Snow Syndrome can directly impact patients by disrupting routine tasks such as reading, driving or even going outside.

Secondly, patients receive a lack of understanding from others. Visual Snow Syndrome is a little-known condition, even within the medical profession. Consequently, friends, family and doctors are often perplexed when sufferers try to explain their symptoms to them. In some cases, they are dismissed as making everything up, or are told to just get over it. Imagine how you would feel if your doctor or closest family member did not believe that you had a condition that was ruining your life.

Thirdly, due to the lack of awareness and information about the condition, patients do not understand their own condition. For years a patient may suffer from VS, and since they often receive no diagnosis or a misdiagnosis from their doctors, they do not know what is happening to them. For many, not knowing what is wrong with them is the worst part of the condition. Many feel that they are alone, and become anxious that their condition will worsen. As fully explained on the About page, this is why this charity was created – to raise awareness of the condition so that people can understand their condition from the very beginning; this can help save years of worrying and help patients come to terms with VS. 

How can I help the cause?

Donating to The Visual Snow Foundation is not the only way you can get involved.

You could help raise awareness. If you suffer from Visual Snow Syndrome, whilst you may understandably want to keep the condition to yourself, you could spread the word and educate others. This could be done on a small scale, such as simply opening up to friends and family. You could go even further and do a small fundraiser, or appear in your local newspaper – the choice is yours and the possibilities endless. More likely than not you will feel much better after talking about your experiences. As the cliché goes, a problem shared is a problem halved. Even if you do not have VS, your voice is valuable and can go a long way.

Also, if you have Visual Snow Syndrome you can volunteer to take part in future research and trials, which will hopefully lead to a treatment. For more information on how to do this, click here

Which conditions does VS often get mistaken for or overlap with?

Persistent Migraine Aura Without Infarction

It was previously thought that VS was a specific type of migraine which lasted for a prolonged period of time called Persistent Migraine Aura Without Infarction. The study in 2014 confirmed that VS is a distinct disorder. Interestingly, many VS sufferers do experience migraines, and a study in 2015 found that patients who suffer from migraine tend to suffer from more severe VS symptoms (i.e. migraine aggravates VS symptoms). It also found that the parts of the brain affected by Visual Snow Syndrome are also affected during a migraine indicating that, although they are separate disorders, there is some overlap in the way they affect each other. The same study also notes that there may be a pathophysiological overlap between typical migraine aura and VS.

Hallucinogen Persistent Perception Disorder (HPPD) and drug usage

Drugs do not cause Visual Snow Syndrome; this was recognised in the 2014 study because many patients are children, and therefore cannot have taken any psychotropic drugs. There is, however, a very similar condition called HPPD which is triggered by psychedelic drugs and gives rise to many similar symptoms. As a result, research into either disorder may help to understand the other. Nevertheless, these two conditions should be kept separate, as many VS sufferers do not want to be associated with drug usage. 

Meares-Irlen Syndrome/Scotopic Sensitivity Syndrome (SSS)

Several VS symptoms, including light sensitivity, pattern glare/visual stress and migraines, are also common symptoms of SSS. SSS is a rare visual processing disorder which sometimes accompanies conditions such as dyslexia and autism. It is as poorly understood as VS, and thus will not be discussed in detail here. For further information about SSS, click here. Notably, tinted lenses/glasses have helped some people with SSS, so they may be worth investigating especially if you suffer from pattern glare.

Multiple Sclerosis (MS)

Visual snow and some other symptoms (such as flashing lights) can often be caused by the autoimmune condition MS. MS is where the body attacks its own nerves. This can cause visual symptoms, including visual snow, if the optical nerve is attacked and becomes inflamed (a condition called ‘optic neuritis’). Here, VS-like symptoms are just one aspect of the manifestation of MS, thus it is not standalone VS.

Lyme disease

Some patients believe that their VS symptoms are linked to them contracting Lyme disease. Similarly to MS, the visual symptoms experienced here are part of a larger condition affecting other body parts/senses rather than being standalone VS. The link between Lyme disease and VS has been subjected to very little scientific investigation.

Should VS sufferers visit a doctor?

Yes. Although most doctors do not know what Visual Snow Syndrome is, you should still visit a doctor for three reasons.

Firstly, you can eliminate the possibility of other conditions. For instance, a sudden onset of floaters and flashes (photopsia) can be a sign of retinal detachment, which can lead to blindness. By going to a medical professional you can rule out other disorders, which is in fact one of the requirements outlined in VS' diagnostic criteria.

Secondly, some doctors do know about Visual Snow Syndrome, albeit just a handful, so there is still a chance that you may be properly diagnosed. Even if the doctor does not know about it, it is a chance for you to make them aware of it. I would recommend taking copies of the recent research into VS (see the Resources page); this will help show the doctor that this is a real condition. With some luck, the doctor may then look into the condition and give you a proper diagnosis.

Thirdly, it is always a good thing to make your doctor aware of your health problems. At least your record will be up-to-date, and you and your doctor can track the development of your symptoms over time.

Is there a test to diagnose VS?

Unfortunately, there is no test to diagnose Visual Snow Syndrome. All eye exams produce normal results because VS is a neurological disorder. Additionally, brain scans such as MRIs do not show anything either. Although PET scans did show a neurological difference in patients with VS in a 2015 study, this difference only shows up when comparing large groups of healthy patients to Visual Snow Syndrome patients. Therefore, VS is diagnosed by eliminating the possibility of other disorders, as required by the diagnostic criteria itself.

Who does VS affect?

Visual Snow Syndrome does not discriminate between people; it can and does affect anyone, anywhere. Some people are born with it, whereas others may develop it really late in life. Men and women are equally affected by the condition. The indiscriminate nature of VS highlights why raising awareness of the condition and finding a cure is extremely important. Even if your vision is fine today, you never know what tomorrow may bring for you, your family or your friends. 

How many people does VS affect?

Exactly how many people suffer from VS is unknown. Generally speaking, the reason why it is so difficult to get such data is because people have the condition without realising it (e.g. if they've had it since birth), or have not received a diagnosis for it (e.g. their doctors don't know about it due to lack of awareness, or they don't seek help). Historically VS has been thought of as being a rare condition, but it is now believed by many to be more widespread than initially thought. Notably, the Facebook support group has approximately 8,300 members (on 7th August 2018), but this does not give any true indication of how many people are affected.

Is VS hereditary?

No official research has been conducted into this question. However, informal surveys conducted by the Eye On Vision Foundation (EOVF), the first charity raising awareness and funds for VS, suggests that there is some kind of genetic link. Many sufferers are afraid of passing on their illness to their children, leading some individuals to avoid having children.

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