Visual snow is a chronic 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. In addition to the static, or “snow”, affected individuals can experience additional visual symptoms such as visual images that persist or recur after the image has been removed (palinopsia); sensitivity to light (photophobia); visual effects originating from within the eye itself (entoptic phenomena) and impaired night vision (nyctalopia).
The prevalence of visual snow in the general population is currently unknown. The average age of the visual snow population seems to be younger than for many other neurological disorders. This early onset, combined with a general lack of recognition by health care providers, suggest it is a common problem.
Initial functional brain imaging research suggests visual snow is a brain disorder.
Diagnosis: Based on Symptomology
- A. Dynamic, continuous, tiny dots across the entire visual field, persisting for more than three months
- B. Additional visual symptoms of at least two of the following four types:
C. Symptoms are not consistent with typical migraine visual aura
D. Symptoms are not better accounted for by another disorder
- Palinopsia (persistent recurrence of a visual image and/or trailing images after the stimulus has been removed)
- Enhanced entoptic phenomena*
- Photophobia (sensitivity or intolerance of light, which can cause some people to avoid sunlight, computers, fluorescent lights and car headlights)
- Nyctalopia (impaired night vision)
No current treatment has proven effective for treating visual snow syndrome. Researchers are continuing to investigate potential options. Current evidence suggests the medications that prevent migraine, such as antidepressants or pain medications, do not consistently improve or worsen visual snow syndrome.