Recruiting

Observational Study

Sponsor:

University of Minnesota

Code:

NCT06961864

Conditions

Visual Snow Syndrome

Migraine

Healthy

Eligibility Criteria

Sex: All

Age: 18 - 60

Healthy Volunteers: Accepted

Interventions

Visual Adaptation

Assessments and Questionnaires

Functional Magnetic Resonance Imaging (fMRI)

Magnetic Resonance Imaging (MRS)

Study Details

Brief summary:

The goal of this study is to learn more about the brain pathways and activity involved in creating Visual Snow Syndrome (VSS). The main questions it aims to answer are:

  • Does VSS arise from spontaneous activity in brain pathways?
  • Where in the brain does the activity contributing to VSS arise?
  • How does brain activity contribute to VSS?

Participants will:

1. Undergo assessments and questionnaires to understand visual and mental symptoms, cognitive, and sensory function.
2. Make visual judgements based on images presented to them both inside and outside a magnetic resonance imaging (MRI) machine.
3. Undergo scanning of their brain while inside of an MRI machine.

Conditions

Visual Snow Syndrome

Migraine

Healthy

Study ID

NCT06961864

Start date

Apr 11, 2025

Status verified date

Jan, 2026

Completion date

Mar 31, 2030

Anticipated

Primary completion date

Mar 31, 2030

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 60

Healthy Volunteers: Accepted

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

Study Design

Enrollment

100 participants

Anticipated

Allocation

Non randomized

Intervention Model

Parallel Assignment

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

active comparator: People with Visual Snow Syndrome

placebo comparator: Non-snow Controls

Interventions

Visual Adaptation

Presentation of visual stimuli to quantify the appearance of visual snow or its effects in the visual system of the brain.

Assessments and Questionnaires

Administration of clinical assessments and questionnaires to gather information about visual and mental symptoms, cognitive, and sensory function.

Functional Magnetic Resonance Imaging (fMRI)

7 tesla fMRI data will be acquired during visual paradigms designed to measure neural responses with and without adaptation.

Magnetic Resonance Imaging (MRS)

7 tesla MRS data will be acquired to quantify the concentrations of different brain chemicals in brain regions including visual cortex.

Primary outcome measure

  • Psychophysical Adaptation Task Performance [ Time Frame: 1.5-2 hours per session, with experiments divided across multiple (e.g., 3) sessions ]
  • Functional Magnetic Resonance Imaging (fMRI) Measures [ Time Frame: 1-2 hours per session, with experiments split across multiple (e.g., 3) sessions ]
  • Magnetic Resonance Spectroscopy (MRS) [ Time Frame: 1-2 hours ]

Central Contacts and Locations

Central contacts

Michael-Paul Schallmo, Ph.D.

(612) 273-9130schallmolab@umn.edu

Hannah Moser, Ph.D.

schallmolab@umn.edu

Locations

University of Minnesota

Recruiting

Minneapolis, Minnesota, United States, 55455

Contacts

Michael-Paul Schallmo, Ph.D., Assistant Professor

612-273-9130schallmolab@umn.edu

More Information

Sponsor

University of Minnesota

Last update posted

Jan 14, 2026

Last verified

Jan, 2026

Keywords

  • Visual Snow Syndrome
  • Visual Snow
  • Migraine
  • Floaters
  • Palinopsia
  • Photophobia
  • Nyctalopia
  • Entoptic phenomena
  • Visual trailing
  • Adaptation
  • Magnetic resonance spectroscopy
  • MRS
  • Magnetic resonance imaging
  • MRI
  • University of Minnesota
  • Afterimages
  • Poor night vision
  • Light sensitivity
  • Persistent positive visual phenomena
  • Static

Trial information was received from ClinicalTrials.gov and was last updated on 2026-10-08. This information was provided to ClinicalTrials.gov by University of Minnesota on 2026-01-14. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.