Tinted lenses to treat migraines

Why seeing through customised tinted glasses reduces migraine attacks.

Precision tinted lenses have been used for some time to help reduce the visual disturbances that affect some migraine sufferers. But up until now, we haven’t fully understood how they work.

Now new research, using functional magnetic resonance imaging (fMRI), has produced a possible scientific explanation of the mechanisms behind this drug-free treatment.

Types of headache

The research involved 11 people who frequently have migraine, each paired with 11 ‘controls’ who don’t have the condition. Each migraine sufferer was prescribed precision ophthalmic tints (POTs) designed specifically for them. Each member of the pair was tested using three sets of lenses, their POTs, coloured lenses with different properties and grey lenses – the last two being used as controls.

Specific visual stimuli – highly contrasting stripes or ‘gratings’ – that can give the observer the illusion of shapes, colours and movement, are known to trigger migraines, and in some cases cause seizures in people with epilepsy.

Tinted lenses

Using the fMRI, the researchers saw abnormal brain activity (known as hyperactivation) when the migraine sufferers looked at the intense striped patterns without their individually prescribed POTs. In contrast, when they looked at the same patterns through the tinted lenses, the brain activation was made more normal and participants who had migraine reported a 70 percent reduction in discomfort.

“What this research shows is that there is something different about the brains of people with migraines,” says Professor Arnold Wilkins, of the Department of Psychology, University of Essex. “Their brains are rather too responsive to strong visual stimuli, especially spatially repetitive patterns, such as spots and stripes, to which they would have quite a large response.

“The response can be measured during fMRI, and we have seen that when people wear glasses with a particular tint, their response reduces,” explains Professor Wilkins, who was involved in the research. “The colour of the tint is very specific to each individual. To find out the right colour we show people text illuminated with a coloured light (using a piece of equipment called an Intuitive Colorimeter). They then choose the colour that is optimally comfortable for them. There are exceptions, but usually the lenses chosen will be in shades of blue, green and turquoise.

“The important thing about this research is that it is the first thoroughly objective demonstration of the therapeutic effect of tinted lenses on the brain,” said Professor Wilkins. The research, carried out by scientists from Michigan State University, the University of Michigan, US and the University of Essex, is published in the journal Cephalalgia.