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

Official title

Visual Perception in Visual Snow Syndrome

Overview

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.

Interventions

• Behavioral Visual Adaptation
  Presentation of visual stimuli to quantify the appearance of visual snow or its effects in the visual system of the brain.
• Behavioral Assessments and Questionnaires
  Administration of clinical assessments and questionnaires to gather information about visual and mental symptoms, cognitive, and sensory function.
• Device Functional Magnetic Resonance Imaging (fMRI)
  7 tesla fMRI data will be acquired during visual paradigms designed to measure neural responses with and without adaptation.
• Device 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 measures

• 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]

Secondary outcome measures (1)

• Clinical Symptom Scores [Time frame: 1-2 hours]

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

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Non-randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Basic science

Study locations

United States · 1 center

• University of Minnesota — Minneapolis

Publications

• Montoya SA, Mulder CB, Allison KD, Lee MS, Engel SA, Schallmo MP. What does visual snow look like? Quantification by matching a simulation. J Vis. 2024 Jun 3;24(6):3. doi: 10.1167/jov.24.6.3. PMID 38837169
• Montoya SA, Hillstrom AJ, Allison KD, Mulder CB, Moser HR, Lee MS, Schallmo MP, Engel SA. Visual Snow Is Susceptible to the Motion Aftereffect. Invest Ophthalmol Vis Sci. 2025 Oct 1;66(13):23. doi: 10.1167/iovs.66.13.23. PMID 41085357
• Montoya SA, Mulder CB, Lee MS, Schallmo MP, Engel SA. Adapting to Visual Noise Alleviates Visual Snow. Invest Ophthalmol Vis Sci. 2023 Dec 1;64(15):23. doi: 10.1167/iovs.64.15.23. PMID 38117246

Identifiers

NCT: NCT06961864 · STUDY00014113 · R01EY036005

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗