Visual Snow Syndrome is a relatively unknown and rare neurological disorder with an official diagnosis code (code ICD- 10 53.8). VSS has visual symptoms, non-visual symptoms and comorbidities. It is a syndrome because it involves a collection of co-occurring symptoms.
Patients have continuous disturbances in the visual field (sometimes even with their eyes closed). The most common symptom is a kind of continuous snow or television noise in the entire visual field. When one has only this symptom continuously and for at least three months, one has Visual Snow. In addition, one can also have other numerous visual symptoms (afterimages, palinopsia, nyctalopia, glare, starbursts, sensitivity to light, pulsating vision, blinking vision, etc.) and non-visual symptoms (tinnitus, dizziness, etc.) that can have a major impact on the patient’s quality of life.
When, in addition to Visual Snow, one has additional visual symptoms of at least two of the following four, then one has Visual Snow Syndrome.
- Palinopsia (persistent recurrence of a visual image and/or trailing images after the stimulus is removed);
- Amplified entoptic phenomena (i.e., excessive floaters in both eyes, excessive blue field entoptic phenomenon, self-lighting of the eye, or spontaneous photopsia);
- Photophobia (sensitivity or intolerance to light (sources) which can also cause considerable pain);
- Nyctalopia (impaired night vision).[1]
In addition to a wide variety of symptoms, the disorder also has a wide variety of severity of symptoms. Some patients have very mild and barely noticeable symptoms and some have symptoms so severe that they are very restricted in their daily lives. It can occur at any age in both men and women. Visual Snow Syndrome is considered as a chronic invisible illness.
The disorder causes people to process visual information abnormally, making normal life more difficult for them. Patients see flashing lights, flickering dots and static, which constantly obstruct their field of vision. There is no relief for them even when their eyes are closed. What distinguishes the symptoms of VSS from other transient phenomena is that they are constant, not temporary, which means they do not go away on their own.
The exact cause is still unknown; more research is needed. However, research indicates that there is a likely link between hyperactivity in the visual cortex of the brain and the origin of this syndrome. Moreover, it is a neurological (brain-related) disorder, not an ophthalmic one. It is a brain processing problem that affects a person’s vision, but it is independent of the health of the eyes.
[1] “Visual Snow Syndrome: A clinical and phenotypical description of 1,100 cases”, F. Puledda et al., 2020. Neurology.