PURPOSE OF REVIEW: In this article, we review illustrative case descriptions of 
both primary and secondary visual snow from our clinic. We discuss recently 
proposed criteria for visual snow syndrome and offer a slight modification of 
these criteria. We also discuss the theories on the pathophysiological 
mechanisms of visual snow, as well as the current approach to treatment.
RECENT FINDINGS: Visual snow is a condition where patients see constant, 
innumerable flickering dots throughout the visual field, similar to "TV static." 
Though visual snow was originally described in 1995, there were still fewer than 
10 cases in the literature prior to 2014. In the last 4 years, this has grown to 
approximately 200 cases and there has been a concentrated effort to better 
understand and characterize this condition. It has become apparent that patients 
who see visual snow frequently have additional visual and non-visual symptoms, 
and the consistency of these symptoms has led to proposed criteria for visual 
snow syndrome. When seeing a patient with visual snow, it is important to rule 
out a possible underlying secondary etiology. Patients with visual snow syndrome 
frequently have comorbid migraine, but visual snow appears to be a separate 
entity from persistent migraine aura. The pathophysiology of this syndrome is 
not clear, but recent neurophysiologic and neuroimaging studies have helped 
advance our understanding.