Visual Snow SyndromeNCT07110493
Study of Visual Perception Phenomena: Phosphene Mapping Induced by TMS and Its Relationship With Eye Movements
A study testing Transcranial Magnetic Stimulation (TMS), Electroencephalography (EEG) and Eye-Tracking in people with Visual Snow Syndrome and Color Blindness, run by Skolkovo Institute of Science and Technology at 1 site in Russia.
Trial summary
The purpose of this basic science study is to better understand human visual perception. Phosphenes are flashes of light that can be induced using Transcranial Magnetic Stimulation (TMS). Read more about this study
- Who is it for?
- Ages 18 to 65 yearsHealthy volunteers can take part
- Conditions the study is for
- Visual Snow Syndrome, Color Blindness, Healthy Volunteer
- What is being tested?
- Transcranial Magnetic Stimulation (TMS), Electroencephalography (EEG) and Eye-Tracking
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 50 participants
- Where
- 1 siteRussia
- Study dates
- 10 Sep 2025to 10 Dec 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- For the "Patients with Visual Snow Syndrome" Arm:
- Confirmed diagnosis of Visual Snow Syndrome according to the International Classification of Headache Disorders, 3rd edition (ICHD-3) criteria.
- Presence of persistent, dynamic, tiny dots ("visual snow") across the entire visual field.
- Presence of at least one of the following additional visual symptoms:
- Palinopsia (prolonged afterimages). Photophobia (hypersensitivity to light). Nyctalopia (impaired night vision). Blurred vision. Patients whose symptoms appeared after a SARS-CoV-2 viral illness may be included.
- For the "Color-blind Participants" Arm:
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- Presence of a color perception disorder. Must have a formal diagnosis of color blindness confirmed by specific ophthalmologic tests (e.g., Ishihara, Rabkin, Justova, or Stilling polychromatic plates, or the Farnsworth-Munsell test).
- For the "Healthy Controls" Arm:
- Absence of any active or past neurological, psychiatric, or ophthalmological disorders.
Who cannot join
- General Criteria (Applicable to all participants):
- Use of psychotropic drugs. Any contraindications to Transcranial Magnetic Stimulation (TMS), such as a history of epilepsy, seizures, or metallic implants in the head.
- Pregnancy.
- Specific to the "Patients with Visual Snow Syndrome" Arm:
- Presence of any organic abnormalities in the eyes or visual system identified during a standard ophthalmologic examination.
- Presence of comorbid psychiatric disorders or other medical conditions (e.g., migraine with aura) that could explain the symptoms.
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- Specific to the "Color-blind Participants" Arm:
- Any non-congenital cases of color blindness. Presence of concomitant visual impairments that could affect visual perception independently of color blindness, such as cataracts, glaucoma, or macular degeneration.
- Presence of concomitant neurological or psychiatric diseases, such as schizophrenia, epilepsy, or mood disorders, that could affect the study results.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Russia1 site, 1 recruiting
- Recruiting
Skolkovo Institute of Science and Technology (Skoltech)
Moscow
Akinshin R., 79999810206, Roman.Akinshin@skoltech.ru
About this study
The purpose of this basic science study is to better understand human visual perception. Phosphenes are flashes of light that can be induced using Transcranial Magnetic Stimulation (TMS). The location of these phosphenes is known to change with eye movements, but the exact influence of these movements is not fully understood.
The main questions this study aims to answer are:
Read more
How does stimulating specific areas of the visual cortex relate to where a person perceives a phosphene? How do eye movements affect the accuracy of mapping these sensations? The study will enroll three groups of adults (aged 18-65): patients with Visual Snow Syndrome, color-blind participants, and healthy volunteers.
During the experiment, participants will receive single-pulse TMS to their visual cortex. Simultaneously, their eye movements will be monitored with an eye-tracker, and their brain activity will be recorded with EEG. Participants will be asked to report the location of the perceived light flashes. This will help create a map of the brain areas responsible for visual sensations and clarify how eye movements influence this process.
- Conditions
- Visual Snow Syndrome, Color Blindness, Healthy Volunteer
- Being tested
- Transcranial Magnetic Stimulation (TMS), Electroencephalography (EEG), Eye-Tracking
- Medical subject headings
- visual snow syndrome, Color Vision Defects
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Transcranial Magnetic Stimulation (TMS)Device
Single-pulse TMS is applied to specific areas of the visual cortex to non-invasively induce the perception of phosphenes (brief flashes of light). Stimulation is delivered using a TMS device, with the operator controlling the intensity and frequency parameters to a level equal to the phosphene-evoking threshold. During stimulation, participants are seated comfortably and asked to report the location of perceived phosphenes on a monitor and a physical grid, helping to map the cortical visual field.
Electroencephalography (EEG)Device
Continuous brain electrical activity is recorded using a 128-channel gel-based EEG system (Skoltech). The EEG cap is fitted to the participant's head to capture neural responses with high temporal resolution throughout the session. The collected data is used to analyze brain activity changes, including the P300 component and other event-related potentials, to identify neural correlates of phosphene perception and the effects of TMS.
Eye-TrackingDevice
Eye movements are continuously monitored using a Tobii Defusion 2 eye-tracker (Skoltech) operating at 60 Hz. This device provides high-accuracy measurements of gaze fixation and saccades. Participants are instructed to fixate their gaze on one of five predetermined points on a screen (center, top, bottom, left, right), with the fixation point being determined randomly for each trial. The eye-tracking data is analyzed to assess the influence of gaze position on phosphene localization and to study any stimulation-induced changes in eye movement patterns.
| Study group | Role | What they receive |
|---|---|---|
| Patients with Visual Snow Syndrome | Experimental | Participants diagnosed with Visual Snow Syndrome according to ICHD-3 criteria. This group will undergo TMS, EEG, and eye-tracking to study the mechanisms of visual perception. Receives: Device: Transcranial Magnetic Stimulation (TMS); Device: Electroencephalography (EEG); Device: Eye-Tracking |
| Color-blind Participants | Experimental | Participants with a confirmed diagnosis of color blindness. This group will undergo TMS, EEG, and eye-tracking to compare visual processing with other groups. Receives: Device: Transcranial Magnetic Stimulation (TMS); Device: Electroencephalography (EEG); Device: Eye-Tracking |
| Healthy controls | Active comparator | Healthy volunteers with no history of neurological, psychiatric, or visual disorders. This group serves as a baseline to compare the findings from the experimental arms. Receives: Device: Transcranial Magnetic Stimulation (TMS); Device: Electroencephalography (EEG); Device: Eye-Tracking |
What is being measured
The primary outcome is the main question the study is designed to answer.
Topographic Map of Phosphene Localization
Creation of a map showing the correlation between specific stimulated areas of the visual cortex and the reported location of perceived phosphenes in the visual field. The map is generated based on participant reports during TMS stimulation.
Measured: During the single study visit (session duration is 4 hours).
Secondary outcomes (3)
Correlation between Eye Movements and Phosphene Localization
Analysis of eye-tracking data to quantify the influence of gaze fixation points and saccadic eye movements on the reported location of TMS-induced phosphenes.
Measured: During the single study visit (session duration is 1-4 hours).
Change in Brain Activity measured by EEG
Analysis of EEG data, including tensor analysis and the P300 event-related potential, to identify changes in brain activity and correlations with phosphene perception and localization.
Measured: During the single study visit (session duration is 1-4 hours).
Change in Psychomotor Performance
Assessment of visual-motor coordination and attention levels measured by a psychomotor test. The test requires participants to track a moving target on a screen. Performance is measured by the number of errors (deviations from the target).
Measured: Baseline (before TMS session) and after the TMS session (approximately at 4 hours).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Aug 2025
- Study start10 Sep 2025 (estimated)
- Primary completion10 Dec 2026 (estimated)
- Study completion10 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Visual Snow SyndromeStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 50 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Skolkovo Institute of Science and Technology
- Sponsor type
- University, hospital or other
- Collaborators
- I.M. Sechenov First Moscow State Medical University
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07110493
- Sponsor's protocol ID
- Skoltech-N15
- Status last verified
- Jul 2025
- First submitted
- 31 Jul 2025
- Last updated
- 7 Aug 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 7 Aug 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Study of Visual Perception Phenomena: Phosphene Mapping Induced by TMS and Its Relationship With Eye Movements
- ClinicalTrials.gov ID
- NCT07110493
- Acronym / sponsor ID
- Skoltech-N15
- Conditions
- Visual Snow Syndrome, Color Blindness, Healthy Volunteer
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 50 participants (estimated)
- Lead sponsor
- Skolkovo Institute of Science and TechnologyUniversity, hospital or other
- Collaborators
- I.M. Sechenov First Moscow State Medical University
- Study start
- 10 Sep 2025 (estimated)
- Primary completion
- 10 Dec 2026 (estimated)
- Study completion
- 10 Dec 2026 (estimated)
- First posted
- 7 Aug 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this basic science study is to better understand human visual perception. Phosphenes are flashes of light that can be induced using Transcranial Magnetic Stimulation (TMS). The location of these phosphenes is known to change with eye movements, but the exact influence of these movements is not fully understood.
The main questions this study aims to answer are:
How does stimulating specific areas of the visual cortex relate to where a person perceives a phosphene? How do eye movements affect the accuracy of mapping these sensations? The study will enroll three groups of adults (aged 18-65): patients with Visual Snow Syndrome, color-blind participants, and healthy volunteers.
During the experiment, participants will receive single-pulse TMS to their visual cortex. Simultaneously, their eye movements will be monitored with an eye-tracker, and their brain activity will be recorded with EEG. Participants will be asked to report the location of the perceived light flashes. This will help create a map of the brain areas responsible for visual sensations and clarify how eye movements influence this process.
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Patients with Visual Snow Syndrome | Experimental | Device: Transcranial Magnetic Stimulation (TMS), Device: Electroencephalography (EEG), Device: Eye-TrackingParticipants diagnosed with Visual Snow Syndrome according to ICHD-3 criteria. This group will undergo TMS, EEG, and eye-tracking to study the mechanisms of visual perception. |
| Color-blind Participants | Experimental | Device: Transcranial Magnetic Stimulation (TMS), Device: Electroencephalography (EEG), Device: Eye-TrackingParticipants with a confirmed diagnosis of color blindness. This group will undergo TMS, EEG, and eye-tracking to compare visual processing with other groups. |
| Healthy controls | Active comparator | Device: Transcranial Magnetic Stimulation (TMS), Device: Electroencephalography (EEG), Device: Eye-TrackingHealthy volunteers with no history of neurological, psychiatric, or visual disorders. This group serves as a baseline to compare the findings from the experimental arms. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (9 listed)
- Confirmed diagnosis of Visual Snow Syndrome according to the International Classification of Headache Disorders, 3rd edition (ICHD-3) criteria.
- Presence of persistent, dynamic, tiny dots ("visual snow") across the entire visual field.
- Palinopsia (prolonged afterimages). Photophobia (hypersensitivity to light). Nyctalopia (impaired night vision). Blurred vision. Patients whose symptoms appeared after a SARS-CoV-2 viral illness may be included.
- Presence of a color perception disorder. Must have a formal diagnosis of color blindness confirmed by specific ophthalmologic tests (e.g., Ishihara, Rabkin, Justova, or Stilling polychromatic plates, or the Farnsworth-Munsell test).
- Absence of any active or past neurological, psychiatric, or ophthalmological disorders.
Key exclusion criteria (9 listed)
- Use of psychotropic drugs. Any contraindications to Transcranial Magnetic Stimulation (TMS), such as a history of epilepsy, seizures, or metallic implants in the head.
- Pregnancy.
- Presence of any organic abnormalities in the eyes or visual system identified during a standard ophthalmologic examination.
- Presence of comorbid psychiatric disorders or other medical conditions (e.g., migraine with aura) that could explain the symptoms.
- Any non-congenital cases of color blindness. Presence of concomitant visual impairments that could affect visual perception independently of color blindness, such as cataracts, glaucoma, or macular degeneration.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Transcranial Magnetic Stimulation (TMS)Single-pulse TMS is applied to specific areas of the visual cortex to non-invasively induce the perception of phosphenes (brief flashes of light). Stimulation is delivered using a TMS device, with the operator controlling the intensity and frequency parameters to a level equal to the phosphene-evoking threshold. During stimulation, participants are seated comfortably and asked to report the location of perceived phosphenes on a monitor and a physical grid, helping to map the cortical visual field. | Device | Color-blind Participants, Healthy controls, Patients with Visual Snow Syndrome |
| Electroencephalography (EEG)Continuous brain electrical activity is recorded using a 128-channel gel-based EEG system (Skoltech). The EEG cap is fitted to the participant's head to capture neural responses with high temporal resolution throughout the session. The collected data is used to analyze brain activity changes, including the P300 component and other event-related potentials, to identify neural correlates of phosphene perception and the effects of TMS. | Device | Color-blind Participants, Healthy controls, Patients with Visual Snow Syndrome |
| Eye-TrackingEye movements are continuously monitored using a Tobii Defusion 2 eye-tracker (Skoltech) operating at 60 Hz. This device provides high-accuracy measurements of gaze fixation and saccades. Participants are instructed to fixate their gaze on one of five predetermined points on a screen (center, top, bottom, left, right), with the fixation point being determined randomly for each trial. The eye-tracking data is analyzed to assess the influence of gaze position on phosphene localization and to study any stimulation-induced changes in eye movement patterns. | Device | Color-blind Participants, Healthy controls, Patients with Visual Snow Syndrome |
Primary outcome
Topographic Map of Phosphene Localization
Time frame: During the single study visit (session duration is 4 hours).
Creation of a map showing the correlation between specific stimulated areas of the visual cortex and the reported location of perceived phosphenes in the visual field. The map is generated based on participant reports during TMS stimulation.
3 secondary outcomes
Correlation between Eye Movements and Phosphene Localization
Time frame: During the single study visit (session duration is 1-4 hours).
Change in Brain Activity measured by EEG
Time frame: During the single study visit (session duration is 1-4 hours).
Change in Psychomotor Performance
Time frame: Baseline (before TMS session) and after the TMS session (approximately at 4 hours).
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Aug 2025.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Transcranial Magnetic Stimulation (TMS), Electroencephalography (EEG) and Eye-Tracking in people with Visual Snow Syndrome and Color Blindness, run by Skolkovo Institute of Science and Technology at 1 site in Russia.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 9 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 7 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Russia. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Akinshin R. (79999810206, Roman.Akinshin@skoltech.ru), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Topographic Map of Phosphene Localization (time frame: During the single study visit (session duration is 4 hours).). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 Aug 2025.