Study of Visual Perception Phenomena: Phosphene Mapping Induced by TMS and Its Relationship With Eye Movements

Launched by SKOLKOVO INSTITUTE OF SCIENCE AND TECHNOLOGY · Jul 31, 2025

Keywords

ClinConnect Summary

This study is exploring how our brain processes visual information by looking at a phenomenon called phosphenes—flashes of light people can see when certain parts of the brain’s visual area are stimulated using a safe technique called Transcranial Magnetic Stimulation (TMS). Researchers want to understand how where these flashes appear changes when your eyes move and how eye movements affect the accuracy of mapping these sensations in the brain. The study includes three groups of adults aged 18 to 65: people with a condition called Visual Snow Syndrome (who see tiny, persistent dots in their vision), people with color blindness, and healthy volunteers with no vision or brain disorders.

If you join, you’ll receive brief, painless magnetic pulses to your visual brain area while your eye movements and brain activity are recorded. You will be asked to describe where you see the flashes of light during the test. This helps researchers create a clearer map of how different parts of the brain handle visual sensations and how eye movement plays a role. To participate, you need to fit into one of the groups based on your health: a confirmed diagnosis of Visual Snow Syndrome, diagnosed color blindness, or no vision or neurological problems. Certain conditions like epilepsy, pregnancy, or use of specific medications would mean you cannot join. This study is currently recruiting volunteers and could help improve our understanding of vision and related disorders.

Gender

ALL

Eligibility criteria

• Inclusion Criteria:
• 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:
• • 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.
• Exclusion Criteria:
• 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.
• 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.