MICHIGAN STATE (US) — By normalizing activity in the brain’s visual cortex, precision-tinted lenses are able to ease the often debilitating pain experienced by migraine sufferers.
The visual cortex is located at the back of the brain and is responsible for processing visual information.
As part of a new study, published in the journal Cephalalgia, researchers used functional magnetic resonance imaging to focus on specific visual stimuli known to trigger migraines. These intense patterns—high contrast stripes or gratings—can give the illusion of shape, color, and movement, not only triggering migraines but also causing seizures in some photosensitive epileptics.
Participants first were prescribed tinted lenses with an intuitive colorimeter, a device used to illuminate text with different colored lights, creating for each test participant an optimal color of light that led to the greatest comfort by reducing distortion.
Tinted lenses with this optimal color were created and given to each test subject, along with two other sets of tinted lenses without the optimal color. In addition, each patient was paired with a migraine-free control subject, who also was tested with that patient’s three sets of lenses.
Once in the fMRI machine, subjects were exposed to a range of striped patterns while their brain images were acquired. Then the researchers analyzed the effect of the tinted lenses on the activation of the different visual areas of the brain.
Specifically, the tinted lenses decreased hyper-activation for migraine sufferers in visual area V2 of the visual cortex of the brain.
Although patients reported some relief (a 40 percent improvement) using the control lenses, the precision-tinted lenses had a significant effect (70 percent improvement) when viewing the stressful stripes.
“The specific characteristics of activation we recorded could provide a potential biomarker for identifying those migraine patients suffering visual cortical hyper-activation,” says Jie Huang, professor of radiology at Michigan State University.
“This biomarker could prove useful not only for further evaluation of tinted lenses but also for studying the effectiveness of drugs to prevent migraine headaches.”
Researchers from the University of Michigan and the University of Essex in England contributed to the study.
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