According to the Rare Disease Database,1 "Visual snow is a neurological disorder characterized by a continuous visual disturbance that occupies the entire visual field and is described as tiny flickering dots that resemble the noise of a detuned analog television." It is also referred to as visual static or persistent positive visual phenomena. It is unknown how common this condition is because it was only discovered within the past decade, and research to understand it better has been sparse. But it does seem to affect people earlier in their lives than many other neurological disorders.
In this article, we will go into more detail about the following areas regarding visual snow syndrome.
- What are the other symptoms of visual snow syndrome?
- How is visual snow syndrome diagnosed?
- What causes visual snow syndrome?
- How is visual snow syndrome treated?
- Is there a cure for visual snow syndrome?
- Some common misconceptions about visual snow syndrome
- What it's like to have visual snow syndrome
- Where can I get more information and support if I have visual snow syndrome?
What are the other symptoms of visual snow syndrome?
Aside from the above-mentioned "static," other possible symptoms include:Palinopsia (continuing to see the "shadow" of an image after you're no longer looking at it)
- Photophobia (sensitivity to light)
- Entoptic phenomena (seeing things within the eye as part of the visual field, such as "floaters.")
- Nyctalopia (night blindness or impaired night vision)
How is visual snow syndrome diagnosed?
Aside from the above-mentioned "static," other possible symptoms include:
- Palinopsia (continuing to see the "shadow" of an image after you're no longer looking at it)
- Photophobia (sensitivity to light)
- Entoptic phenomena (seeing things within the eye as part of the visual field, such as "floaters.")
- Nyctalopia (night blindness or impaired night vision)
As with many poorly-understood disorders, the diagnosis is through a clinical exam and one of exclusion. Those diagnosed typically have a normal eye exam or at least one that rules out other conditions as the cause of their symptoms. Migraine aura must also be ruled out as the cause of the visual disturbance.
Additional criteria for diagnosis include visual static, which can either be a combination of black/white/grey, colors, flashing white, or transparent. Symptoms must be present continuously for at least three months.
Additionally, patients must have at least two of the other symptoms mentioned in the previous section.
What causes visual snow syndrome?
The causes of this condition are still under investigation. However, there is a strong correlation between visual snow and tinnitus (ringing in the ears), which leads some experts to suggest that the snow is a form of "visual tinnitus," or perhaps a sensory processing disorder of some sort. At this time, all that is known is that it appears to be a dysfunction originating in the brain.1
Visual snow is sometimes mistaken for a prolonged migraine aura, which should be examined as comorbidity (additional condition) during diagnosis. It is not uncommon for patients with visual snow to have headaches; as one can imagine, the eyes are straining to focus.
A similar visual effect also results from taking hallucinogens and is called HPPD or hallucinogen persisting perception disorder. Obviously, if these drugs were not consumed, then that diagnosis is ruled out.
There is also a theory that visual snow syndrome is related to extra pressure on the nerves connected to the eyes due to intracranial hypertension (high pressure within the skull).2 However, once again, there are so few patients that have been evaluated so far that it's difficult to say if there is a definitive link.
Anecdotally, I know many people with CSF leaks who also experience visual snow. In their case, they would typically have low intracranial pressure (intracranial hypotension).
How is visual snow syndrome treated?
Unfortunately, there is no known effective treatment at this time. Some drugs have been tried, such as migraine prevention medications, antidepressants, and pain medications. Reports are of symptom alleviation without complete remission in some patients. There is not a lot of data available since the diagnosed population is so small. There have not been enough clinical trials either. More investigation is needed to help this patient population.
Is there a cure for visual snow syndrome?
There is no cure at this time. Hopefully, there will be helpful treatments available in the future as more is learned about this condition.
Some common misconceptions about visual snow syndrome
Many people with this diagnosis were told for years that their vision was normal because nothing showed up during the examination of their eyes. As with many poorly-understood conditions, patients are often blamed, treated like hypochondriacs, or disregarded because of ignorant healthcare providers.
A doctor may also insist that the visual disturbances are "just migraine auras" and have the patient trial many drugs that are typically prescribed for migraine treatment or prevention. These drugs may alleviate some but not all symptoms and the patient is left with the possibility of an undiagnosed condition that is not being addressed.
If a provider is aware of HPPD, they may also believe a patient is lying about hallucinogen consumption. I advise that if someone encounters this situation, they insist that the physician perform a drug test to rule out hallucinogens as a contributing factor. Once this theory is disproven, insist that the physician continue investigating the cause. The best person to diagnose visual snow syndrome is an eye doctor who is knowledgeable about rare disorders.
Rest assured, this issue is not all in your mind. While this rare diagnosis seems like fiction, it is very real and there are experts in healthcare who have documented its existence.
What it's like to have visual snow syndrome
If you think that all of this doesn't sound too bad, imagine one of the following scenarios:
1. You're at the pool or beach all day with a pair of glasses on. Your glasses get splashed with water, and you're not allowed to wipe them off. You have to look at everything through the water drops.
2. You're driving during a rainstorm, where there is just enough rain for beads of water to be all over your windshield. You can't use your wipers to clear them away. You have to drive for hours like that.
That's how my vision is, all day, every day. At night sometimes, the static is multi-colored, which is actually kind of neat. I'm glad it only happens at night when I'm not using my eyes. Otherwise, I imagine it would be harder to see than it already is.
If you'd like to experience visual snow for yourself (or confirm that your symptoms match visual snow syndrome), you can use a visual snow simulator. See reference #3 below for a link to copy and paste.
Where can I get more information and support if I have visual snow syndrome?
There is a visual snow support group on Facebook where you can connect with others.4 The Visual Snow Initiative website has a page for doctors and specialists.5 Lastly, the Rare Diseases website keeps an updated list of clinical trials by the name of disease or disorder.6 You can check there for updates on available trials for visual snow syndrome and other conditions.
References
1. https://rarediseases.org/rare-diseases/visual-snow-syndrome/
2. https://journals.lww.com/neurotodayonline/blog/neurologytodayconferencereporteramericanheadachesocietyannualmeeting/pages/post.aspx?PostID=36
3. https://visionsimulations.com/visual-snow.htm
4. https://www.facebook.com/vssupport/
5. https://www.visualsnowinitiative.org/visual-snow-syndrome-doctors-and-specialists/
6. https://rarediseases.org/for-patients-and-families/information-resources/info-clinical-trials-and-research-studies/