May 27, 2011 -- Precision tinted lenses can help reduce the discomfort experienced by some migraine sufferers by normalizing activity in the brain, a study suggests.
Some people who suffer migraines ''are highly susceptible to stressful visual stimuli," says study researcher Jie Huang, PhD, associate professor of radiology at Michigan State University.
"The stimuli produce discomfort and perceptual illusions, illusions of color, shape, and motion," he tells WebMD.
His earlier studies found that this susceptibility to visual stimuli is linked with excess activation in the brain's visual cortex.
The excessive brain activity, in turn, can sometimes induce a migraine. The specially tinted glasses, he found, may normalize the brain activity.
Testing Migraine Patients
Huang and his colleagues already knew that certain striped patterns can trigger migraines in some people.
They tested 11 people with migraines and 11 without. The researchers made lenses known as precision ophthalmic tints for each person. They also made two other pairs of lenses, gray and colored, as comparisons.
Next, the participants were placed in a functional MRI machine and exposed to a range of striped patterns with different likelihoods of triggering distortion and discomfort.
Patients reported some relief with all the lenses, but the precision ones worked better.
''Wearing the control lenses reduced the degree of visual discomfort by about 40% compared to that without lenses, and wearing the precision ophthalmic tints resulted in a 70% reduction," Huang says.
The precision lenses suppressed brain activation in those with migraines.
Both the migraine and migraine-free patients responded in a similar way to the non-stressful striped patterns.
"It shows that although wearing sunglasses could help those with migraine to reduce visual stress, wearing individually prescribed POTs [precision ophthalmic tints] may further reduce the visual stress significantly in comparison to that with wearing the sunglasses," Huang says.
While the visual stress for the study was produced by an experimental stimulus in the study, Huang says it can also result from such activities as reading, watching TV, or working on the computer.
The precision lenses can be put into regular glasses, Huang says. For the study, Cerium Visual Technologies, Ltd, in the U.K. provided the lenses.
Huang's co-researcher, Arnold Wilkins, designed the Intuitive Colorimeter, the device used in the study to evaluate the best hue of light for visual comfort. He receives from the UK Medical Research Council a portion of royalties on sales of the colorimeter but not on the lenses sold.
''The idea of using tinted lenses to reduce migraine and visual discomfort is not a new one," says Kathleen Digre, MD, professor of neurology and ophthalmology at Moran Eye Center at the University of Utah. She reviewed the study findings for WebMD but was not involved in the study.
She and her colleagues offer a filter lens, known as the FL-41, that she has found useful in patients with migraine headaches or other light sensitive conditions.
"It's a tinted lens first used in England and studied in schoolchildren," she says. "Wearing it reduced headaches by half."
The important finding in the new study, she says, is the use of the MRI. "It showed something in the brain changed [with the lenses]," she says, rather than relying only on subjective reports of reduced visual discomfort.
However, she adds, ''We don't know if it improved the headache."
"This is a work in progress," she says. The study needs to be replicated.
Her center adds the FL-41 filter to existing lenses. However, she says, it would be worth a try for migraine sufferers to simply put on sunglasses to reduce visual discomfort.
Robert Daroff, MD, professor of neurology at Case Western University School of Medicine, agrees that sunglasses would be worth a try. "Sunglasses are better than no sunglasses," he says.
The remedy applies to only a small portion of migraine sufferers, says Daroff, who is past president of the American Headache Society. Very few migraine sufferers, he says, have migraine exclusively triggered by visual stimuli.