Two hundred and forty-eight cases of visual snow: A review of potential inciting events and contributing comorbidities

Abstract

Objective To review characteristics and outcomes of all cases of visual snow seen at our institution, with attention to possible triggering events or comorbidities. Methods This is a retrospective case series of patients seen at our tertiary care center from January 1994 to January 2020. Charts were reviewed if they contained the term “visual snow”. Results Of the 449 charts reviewed, 248 patients described seeing visual snow in part or all of their vision. Thirty-eight reported transient visual snow as their typical migraine aura. Of the remaining 210 patients, 89 were reported to have either an inciting event or contributing comorbidity for their visual snow symptoms, including: Post-concussion (n = 15), dramatic change in migraine or aura (n = 14), post-infection (n = 13), hallucinogen persisting perception disorder (n = 10), ocular abnormalities (n = 7), idiopathic intracranial hypertension (n = 4), neoplastic (n = 1), and posterior cortical atrophy (n = 1). Some patients had partial improvement with benzodiazepines (n = 6), lamotrigine (n = 5), topiramate (n = 3) and acetazolamide (n = 3). Presenting characteristics were similar, but patients with visual snow attributed to an inciting event or contributing comorbidity were more likely to have some improvement in their symptoms by last follow-up compared to spontaneous visual snow ( p < .001). Conclusions Though most cases of visual snow are spontaneous, potential secondary causes should be recognized by clinicians. Patients who develop visual snow after an inciting event or related to an underlying comorbidity may have a better prognosis than those in whom it develops spontaneously. In select cases, treatment of the suspected underlying cause may significantly alleviate the otherwise typical intractable visual disturbances associated with visual snow.

Visual Snow Syndrome as a Network Disorder: A Systematic Review

“…Floaters can be caused by degenerative changes in the vitreous body including liquefaction ( 22 , 23 ). According to the above-mentioned studies, between 61% ( 16 ) and 100% ( 24 ) of VSS patients are perceiving them in an excessive way, i.e., far more than normal vitreous floaters and far more than expected from ophthalmological findings.…”

“…The “selflight of the eye” is light or colored clouds seen with closed eyes ( 26 ) and perceived by 16% ( 16 ) to 71% ( 11 ) of VSS patients. The cause of this phenomenon is unknown.…”

“…Photopsia, reported in 24% ( 15 , 16 ) to 63% ( 4 , 11 ) of VSS patients, are “flash-like” positive visual phenomena with sudden onset and brief duration ( 28 ). The origin in different diseases can be generated by almost all components of the visual path from ocular mechanical disturbances to affections of the secondary visual pathways ( 28 ).…”

“…In the literature, it has often been described in patients with retinal diseases (especially affecting the rod cells), but the inability to adapt to light conditions might involve almost all components of the visual pathway ( 29 ). About 28% ( 16 ) to 78% ( 11 ) of VSS patients are affected.…”

“…Photophobia, which is experienced by 44% ( 16 ) to 81% ( 11 ), is hypersensitivity, discomfort, or even pain caused by “normal” light ( 27 , 30 ). Eren et al ( 27 ) compared a group of 19 VSS patients to a group of 19 controls matched for age, sex, migraine, and aura using the Leiden Visual Sensitivity Scale ( 31 ).…”