Visual snow syndrome (VSS) is a complex clinical condition presenting with visual as well as non-visual symptoms. The underlying biological mechanisms are poorly understood, though recent research suggests the syndrome likely results from widespread alterations in sensory processing systems. Ophthalmic, neurological, and structural brain imaging examinations are typically normal, rendering the diagnostic process particularly challenging. Future studies must define reliable methods of phenotyping VSS with a view to developing effective medical interventions.
What is VSS, and who does it affect?
First described in the literature in 19951, the term ‘visual snow’ has only been in use since 20052. VSS has since become further clinically characterised, leading to its recent recognition as a syndrome3. However, generalised unfamiliarity with VSS within the medical community has led to frequent difficulties in recognising VSS in patients.
Patients typically present with persistent visual disturbances consisting of bilateral pan-visual ‘static’, similar to that of an out-of-tune analogue TV, often persisting when the eyes are closed4. Frequently reported comorbidities include additional visual symptoms such as palinopsia, hypervigilance to blue field entoptic phenomenon, photophobia and nyctalopia3,5. Common non-visual symptoms include comorbid migraine, tinnitus, lethargy, anxiety and impaired concentration3. Such symptoms can be intrusive and debilitating, with day-to-day life impairments experienced by many who seek out medical attention.