Study Explains How Tinted Lenses Offer Relief from Migraines

(G.L. Kohuth/Michigan State Univ.)

Researchers at Michigan State University in East Lansing have discovered the process that enables precision-tinted lenses to relieve migraine sufferers of their headaches. Radiologist Jie Huang and colleagues from MSU and other institutions published their findings in the online issue of the journal Cephalalgia (free for a limited period of time).

Scientists studying migraines have known for some time that tinted lenses helped relieve their headaches, but the reasons remained something of a mystery. Huang and his team showed that glasses with a tint calibrated specifically for each migraine sufferer normalize the activity in the brain’s visual cortex, responsible for processing visual information.

Earlier studies have documented how hyper-activation, a form of specific and abnormal brain activity, occurred when migraine sufferers saw intense patterns. These patterns — high contrast stripes or gratings — can give the illusion of shape, color, and movement. Not only can the intense shapes trigger migraines, but they are also attributed to seizures in some epileptics.

In this study Huang and his team focused on specific visual stimuli known to trigger migraines. Participants first were prescribed tinted lenses with a device that illuminated text using different colored lights. This device, called an intuitive colorimeter, created for each test participant an optimal light color that led to the greatest comfort by reducing distortion.

Each test subject received tinted lenses with this optimal color, with two other sets of tinted lenses without the optimal color. Each patient was also paired with a migraine-free control subject, who was tested with that patient’s three sets of lenses.

Study participants viewed a set of striped test images while in a functional magnetic resonance imaging (fMRI) machine. An fMRI machine uses magnetic resonance imaging to display and measure tiny metabolic changes that take place in an active part of the brain. The researchers then analyzed the effect of the tinted lenses on the activation of the different visual areas of the brain.

The team found that the tinted lenses decreased hyper-activation for migraine sufferers in a visual area of the brain’s visual cortex. The test subjects experienced a 70 percent improvement when viewing the stressful striped patterns. This rate of improvement was significantly higher in statistical terms than the 40 percent improvement recorded by the control subjects.

Huang believes the findings “could prove useful not only for further evaluation of tinted lenses but also for studying the effectiveness of drugs to prevent migraine headaches.”

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