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What is Visual Snow Syndrome?
Visual Snow Syndrome (VSS) is characterized by the experience of innumerable flickering specks/dots/static superimposed on their vision at all times. Many describe this experience as looking similar to "television snow". In addition to the snow itself, other symptoms of VSS include strong afterimages, streaks left behind moving objects, light sensitivity, blue field entoptic phenomena, poor night vision, tinnitus (ringing/buzzing in the ears), and migraine. These symptoms can interfere with daily tasks such as driving and reading.
Images of Typical Symptoms Experienced by Those with Visual Snow Syndrome
Visual Snow Syndrome (VSS) versus Visual Snow
VSS is defined by the presence of visual snow as well as at least two of the additional visual symptoms shown above (afterimages, trails/streaks, blue field entoptic phenomena, light sensitivity, poor night vision).
Prevalence
A study by Kondziella et al. estimated the prevalence of VSS to be between 1.4-3.3% of the population in 2020. Many people are unaware that they may have VSS, especially if they have experienced these symptoms for their entire lives.
Other Conditions that are Commonly Associated with VSS
Several studies have reported increased incidences of anxiety, depression, impaired concentration, and fatigue in VSS. It is still unclear if/how these other conditions are related to VSS. Additionally, about 75% of people with VSS experience tinnitus and/or migraine. Recently, Solly et al. (2021) found a correlation between VSS and symptoms of depersonalization/derealization.
Lack of Treatments
There are no effective treatments for VSS. Some people report that wearing color-tinted lenses or watching visual snow relief videos can minimize symptoms. One of the reasons that treating VSS is so difficult is that the mechanisms underlying the syndrome are still poorly understood.
by qimono on pixabay
What Causes VSS?
We still aren't sure what mechanisms underlie VSS. We do know that assessments of eye and optic nerve health are typically normal in VSS, indicating that VSS probably arises in the brain.
Does VSS Impair Vision?
While VSS can make tasks like reading and driving more difficult, people with VSS typically have normal acuity, or the ability to discern letters at a given distance (you may have experienced a visual acuity test at an eye doctor's clinic). Another common measure of vision assesses how big of a difference in luminance between an object and its background is required for that object to be visible, which is referred to as contrast sensitivity. There is inconclusive evidence as to whether people with VSS have poorer, stronger, or no difference in contrast sensitivity. Further research is needed to determine how symptoms of VSS interfere with visual function.
History
Due to the similar symptoms Visual Snow Syndrome and migraines share, VSS was often diagnosed as a migraine. For many years it remained this way until Liu Y published a research article in 1995 on four patients who had symptoms that were similar to a migraine but were not quite the same. For instance, the patients had an absence of a severe headache. Liu Y determined through the four patients that there were additional visual, non-visual, and non-perceptual symptoms that distinguished a migraine from what is now known as Visual Snow Syndrome.
Read Liu Y's research article here.
Similar to misdiagnosing VSS as a migraine, it has also been misdiagnosed as Psychogenic Disorder, Post-Hallucinogenic Flashbacks, and a side effect of drug abuse.
To learn more about VSS
Check out visual snow on Wikipedia