Researchers have made use of fMRI (functional magnetic resonance imaging) to show how coloured glasses bring migraine relief by normalizing brain activity. When individuals with migraine saw intense patterns, specific abnormal brain activity was observed by the researchers. The effect was considerably reduced with tinted lenses.
Specific visual stimuli known for triggering migraines were focused on. These high contrast stripe patterns can give the illusion of movement, colour and shape. Not only do these patterns trigger migraines but can also result in seizures in individuals with photosensitive epilepsy.
Participants were tested prior to the brain imaging and POTs (precision ophthalmic tints) were prescribed. Prior research has indicated that about 42% of individuals who suffer from migraine with aura saw the frequency of migraine cut in half on days whenever wearing POTs. An Intuitive Colorimeter was made use of for illuminating text with coloured light, manipulating chromaticity (saturation and hue) at constant luminance. This gave an optimal chromaticity of light for each individual that resulted in the greatest comfort, decreasing perceptual distortion. The individuals then looked at stressful striped patterns which were illuminated with optimal coloured light settings for efficacy screening. These readings were made use of for making both effective POTs for each individual and also 2 other control pairs of coloured and grey lenses with slightly different properties. Each individual who suffered from migraine was paired with a control who was free from migraine, and who was also tested with the 3 sets of lenses.
Individuals were exposed to a variety of striped patterns in the fMRI machine. These striped patterns had varying chance of causing discomfort and distortion. Even though individuals noted around 40% relief making use of all of the lenses, the POT lenses had a 70% discomfort reduction effect when looking at the stressful stripes. Both migraine and control individuals responded in the same way to the stripe patterns which were not stressful, and in these cases all 3 lenses did not make any difference to the result. Cortical activation for individuals with migraine was specifically suppressed in visual area V2 of the brain’s occipital cortex with the POTs, and this cortical activation suppression was extended to other visual areas as well.
The trigger of these responses to specific visual stimuli will probably differ from the photophobia that individuals with migraine typically report during an attack.