Visual Snow Not Caused By Drug Use, Migraine

An underreported condition known as visual snow is not likely the product of illicit drug use, as it was once believed to be, researchers said. 

Visual snow presents as a swirls of color, shadows, and flashing, swimming dots in a person’s every day vision, reported Christoph Schankin, MD, of the University of California San Francisco, at the American Academy of Neurology’s annual meeting. 

The condition has never been studied in large numbers, and appears only sporadically in medical literature, where it is described as likely the effect of hallucinogen intake or a strange form of migraine aura.  These factors, along with prompting from advocacy groups led Dr Schankin to begin his study.

Following 120 people reporting similar symptoms, researchers found that although migraines are common with visual snow, it affects a large number of people with no history of migraine or hallucinogen use. 

Substantial symptom variation was present, so researchers confined their study to 57 of those experiencing solid, unmoving black and white dots in their every day vision. Participants also reported darting white objects when looking at the sky, colored waves when eyes were closed, poor night vision, and trails behind moving objects,

Although 54% reported migraines, Dr Schankin stressed that the two conditions were unrelated. 

“Visual snow, or Positive Persistent Visual Disturbance, is a unique disease entity presenting clinically distinct from migraine with aura,” he concluded.

-Michael Potts