Migraine sufferers really do experience relief when they use tinted specs or lenses, and for the first time functional magnetic resonance imaging appears to provide neurological proof, researchers from Michigan State University and the University of Michigan reported in the journal Cephalalgia. (Cephalalgia means headache. From the Greek 'kephale', meaning 'head', and Greek 'algos', meaning 'pain')
The authors explained that experts had been unable to explain why tinted glasses helped relieve migraine symptoms. This study has shown how colored glasses tailored to each individual migraine sufferer worked by stabilizing brain activity.
When migraine sufferers saw intense patterns the scientists were able to observe hyperactivation (abnormal brain activity), which was reduced by the effects of tinted lenses.
Jie Huang focused on certain visual stimuli known to bring on migraine symptoms. These patterns, gratings or high contrast stripes can give the illusion of movement, color and shape. They not only set off migraines, but among individuals with photosensitive epilepsy can bring on seizures.
Before undergoing brain scans, individuals were tested and prescribed POTs (precision ophthalmic tints) with an Intuitive Colorimeter.
According to previous studies, about 42% of those who had migraines with aura had experienced a 50% fall in migraine frequency when they wore POTs.
The researchers illuminated text with colored light, manipulated hue and saturation at constant luminance with the colorimeter. They managed to give each participant their optimal chromaticity of light, resulting in greatest comfort, thus reducing perceptual distortions. They were then asked to look at stressful striped patterns which were illuminated with their ideal colored light setting to screen for efficacy.
The readings were used to generate individually designed POTs, as well as two more pairs of colored and grey lenses which would serve as controls (they had slightly different properties).
The fMRI (functional magnetic resonance imaging) study involved 11 individuals who frequently suffered from migraines. Each migraine sufferer was paired with a control (non migraine person). The control was also tested with the same three sets of lenses.
The participants were placed in the imaging machine and exposed to a variety of striped patterns with varying probabilities of provoking discomfort and distortion.
The researchers' aim was to observe the effect the POTs might have on the cortical activation that was triggered by the stressful pattern in each visual area of the brain.
About 40% of migraine participants reported some degree of relief with all the lenses. However, 70% reported significant relief when using POT lenses and looking at the stressful stripes.
As far as the non-stressful stripe patterns were concerned, all three lenses made no difference and both migraine sufferers and their paired controls responded similarly.
"The POTs specifically suppressed cortical activation for migraine sufferers in visual area V2 of the occipital cortex of the brain, and this POT-suppressed cortical activation was also extended to the other extra-striate visual areas V3, V3A, and V4.
The reduced cortical activation in V2 by the POTs may have been responsible for the POT-induced suppression of the illusions and distortions, considering that V2 neurons but not V1 neurons in macaque monkeys respond to illusory contour stimuli."
The participants' responses to specific visual stimuli in this study probably differs from the photophobia a migraine sufferer might experience during a migraine attack.
The authors suggest that:
"The specific characteristic of the cortical activation in the extra-striate visual areas they recorded could provide a potential biomarker for identifying those migraine patients suffering cortical hyperactivation. This biomarker could prove useful not only for further evaluation of POTs but also for studying the effectiveness of drugs to prevent migraine."
"fMRI evidence that precision ophthalmic tints reduce cortical hyperactivation in migraine"
Jie Huang, Xiaopeng Zong, Arnold Wilkins, Brian Jenkins, Andrea Bozoki, Yue Cao
Cephalalgia 26 May, 2011.
Written by Christian Nordqvist