ADVERTISEMENT

Photophobia And Magnetism: First Date For An Interesting Liaison

Photophobia describes an experience of discomfort or pain in response to light conditions. In normal conditions, it can be provoked using strong-intensity light. When it is provoked by light at normal intensity, it can be considered a symptom that is observed in many ophthalmological and neurological disorders. The most common conditions in which this alteration occurs are in patients with migraine and patients with ocular pathologies.

In migraine, photophobia is related to functional alterations of the trigeminal system, the thalamus, and the visual cortex. For these reasons, reducing the visual cortex pathological responsiveness to light may improve migraine patients. Non-invasive brain stimulation (NIBS) techniques use a physical agent like magnetic pulses, electrical fields, or ultrasound to modulate the cortical excitability and functions. We described a NIBS technique based on the application of strong static magnetic fields (tSMS) over the cortex. Thus, tSMS applied over the visual cortex can change brain activity and decrease the visual cortex excitability.

ADVERTISEMENT

With the idea of using tSMS in migraine patients, we first studied its effect on experimental photophobia (visual discomfort experimentally induced in healthy subjects by an intense light). The static magnetic field was obtained by using a neodymium magnet. This is a type of rare-earth magnet; it is a permanent magnet made from an alloy of neodymium, iron, and boron with a tetragonal crystalline structure. This material is the strongest type of permanent magnet available in the market.

We performed a crossover, double-blind, sham-controlled study on twenty healthy volunteers. All subjects participated in two experimental sessions at least one week apart with different interventions (tSMS or sham) applied for 10 minutes over the occiput. In each session, subjects were seated in a comfortable armchair in a dark room, facing the wall, and received low-intensity and high-intensity visual stimuli before, during, and after the tSMS (real or sham) interventions. In this way, each session was divided into three blocks of 10 minutes and 16 visual stimuli each (8 low-intensity and 8 high-intensity). Visual stimulation was applied for 1 second every 39 seconds, and after each visual stimulation, subjects were asked to rate visual discomfort, using a visual analog scale (VAS), with 0 for no-discomfort and 10 for very-severe- discomfort. The figure shows a schematic drawing of the helmet with incorporating tSMS and the visual stimulation (LED) we used for our experiments.

Credit: Vanesa Soto-Leon

We found that occipital tSMS reduces the visual discomfort evoked by high-intensity visual stimuli in healthy subjects. Specifically, the mean VAS was lower only for real tSMS compared to sham during the second half of the intervention block.

We conclude that focal static magnetic fields can interfere with responsiveness to high-intensity visual stimulation in healthy population. This result provides motivation for applying this novel NIBS technique, which is both portable and inexpensive, to move towards possible clinical application of tSMS in migraine.

ADVERTISEMENT

These findings are described in the article entitled Transcranial static magnetic field stimulation (tSMS) of the visual cortex decreases experimental photophobia, recently published in the journal Cephalalgia.

Comments

READ THIS NEXT

Agricultural Mechanization: Why It Matters 

The rural population involved in agriculture is aging at a faster rate compared to the urban population. Migration, lack of […]

Map Of Every Florida Beach

Looking at a map of Florida beaches makes you realize just how beautiful Florida’s coastline is. From the famous South […]

Can Ultrasounds Record Cyanobacterial Blooms?

Published by Małgorzata Godlewska European Regional Centre for Ecohydrology of the Polish Academy of Sciences These findings are described in […]

Sea Lion Vs Seal: Here’s The Difference

When comparing a sea lion vs. seal you can spot the difference a few ways, one of which is the […]

Can Material Found In Nature Provide Effective Treatments For Acid Drainage?

Acid drainage (AD) refers to the effluent from mining, metallurgy, and various other industrial operations, including tanneries, electroplating, power plants, […]

HC2H3O2: Chemical Name And Properties

HC2H3O2 is the chemical formula for the organic compound acetic acid. Also called ethanoic acid, acetic acid is a colorless […]

What Are The Reactants Of Photosynthesis And Cellular Respiration?

The reactants of photosynthesis are carbon dioxide and water, meaning during photosynthesis carbon dioxide and water are taken in to […]

Science Trends is a popular source of science news and education around the world. We cover everything from solar power cell technology to climate change to cancer research. We help hundreds of thousands of people every month learn about the world we live in and the latest scientific breakthroughs. Want to know more?