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

Launched by UNIVERSITY OF MINNESOTA · Apr 29, 2025

Keywords

ClinConnect Summary

This clinical trial is focused on understanding Visual Snow Syndrome (VSS), a condition where people see persistent visual disturbances, like "dynamic dots" in their vision. The researchers want to learn more about how the brain works in individuals with VSS compared to those without it. They will investigate whether the symptoms come from activity in specific brain pathways and where this activity takes place in the brain. Participants will complete questionnaires about their visual and mental symptoms, make visual judgments while inside an MRI machine, and undergo brain scans to gather more information.

To be eligible for the study, participants with VSS must be between 18 and 60 years old, have normal or corrected vision, and live within two hours of the study site in Minnesota. They need to have a confirmed diagnosis of VSS and experience specific visual symptoms. Non-participants, who do not have VSS, can also join the study if they meet similar age and vision requirements. Throughout the study, participants can expect to share their experiences, undergo some testing, and contribute to valuable research that could help improve understanding of VSS.

Gender

ALL

Eligibility criteria

• 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