Investigating Brain Function in People With and Without Visual Snow Syndrome Using Adaptation to Visual Stimuli

Inclusion Criteria for People with Visual Snow Syndrome:

• Between the ages of 18 and 60 years old

• Normal (20/25 or better in each eye) or corrected-to-normal vision (MR-compatible glasses will be provided as needed)

• Ability to comply with study instructions

• Individuals who have a current diagnosis of VSS from a neuro-ophthalmologist or meet diagnostic criteria of VSS (experience of dynamic dots across the visual field persisting longer than 3 months and at least 2 of the following additional visual symptoms: palinopsia, entoptic phenomena, trails behind moving objects, photophobia, or nyctalopia)

• Individuals living in Minnesota within 2 hours of the study site

Inclusion Criteria for Non-snow Controls:

• Between the ages of 18 and 60 years old

• Normal (20/25 or better in each eye) or corrected-to-normal vision (MR-compatible glasses will be provided as needed)

• Ability to comply with study instructions

• Individuals living in Minnesota within 2 hours of the study site

Exclusion Criteria for People with Visual Snow Syndrome:

• Not being fluent in English or another language for which interpretation/translation services are available

• A diagnosed or self-reported intellectual disability

• Current substance dependence (besides nicotine), or drug dependence with tolerance or withdrawal within past 12 months

• Hallucinogenic substance use within the past 12 months or hallucinogenic substance use within 12 months prior to onset of VSS symptoms

• Severe central nervous system disease

• Head injury with skull fracture or loss of consciousness for more than thirty minutes

• Presence of a physical problem that would render study measures difficult or impossible to administer or interpret (e.g., visual field loss)

• Age less than 18 years or greater than 60 years

• MRI exclusions (for MR visits only):

• Metal in the body that cannot be approved by the CMRR safety committee

• Pregnancy

• Conditions that affect neuro-hemodynamic coupling

• Claustrophobia

• Inability to lie still for at least an hour

• Weight in excess of 440 lbs

• CT scan exclusion only: Research-related radiation exposure within the last 12 months

• Any vision anomaly aside from VS or refractive error (e.g., strabismus/ crossed eyes, lazy eyes, color blindness)

• Current psychotic episode

Exclusion Criteria for Non-snow Controls:

• Not being fluent in English or another language for which interpretation/translation services are available

• A diagnosed or self-reported intellectual disability

• Current substance dependence (besides nicotine), or drug dependence with tolerance or withdrawal within past 12 months

• Hallucinogenic substance use within the past 12 months

• Severe central nervous system disease

• Head injury with skull fracture or loss of consciousness for more than thirty minutes

• Presence of a physical problem that would render study measures difficult or impossible to administer or interpret (e.g., visual field loss)

• Age less than 18 years or greater than 60 years

• MRI exclusions (for MR visits only):

• Metal in the body that cannot be approved by the CMRR safety committee

• Pregnancy

• Conditions that affect neuro-hemodynamic coupling

• Claustrophobia

• Inability to lie still for at least an hour

• Weight in excess of 440 lbs

• CT scan exclusion only: Research-related radiation exposure within the last 12 months

• Any vision anomaly or refractive error (e.g. strabismus/ crossed eyes, lazy eyes, color blind)

• A personal history of VSS symptoms or a diagnosis with VSS

• Current psychotic episode