Visual Snow Syndrome: Differential Diagnosis and Workup

The definition of VSS is visual snow plus other visual and perceptual symptoms. It is important to divide VSS into "primary" and "secondary." Primary VSS is defined as symptoms that develop without an inciting event or known cause, and secondary VSS is defined as symptoms arising from a secondary cause such as head trauma (immediate or delayed onset), hallucinogenic drugs, or other chronic neurological or ophthalmologic disorders.ICvisualsno