Bright lights and certain patterns can induce perceptual illusions/distortions and visual discomfort in most people as well as headaches in patients with migraines. Visual stimuli are common triggers for migraine attacks, possibly because of a hyperexcitability of the visual cortex shown in patients with migraines. Individually prescribed precision coloured lenses (PCLs) have been shown to reduce perceptual distortions and visual discomfort and to prevent migraine headaches in some patients. Recent studies have demonstrated the normalization of cortical activation and SF tuning in migraineurs when using PCLs, suggesting a neurological basis for the therapeutic effect of these lenses in reducing visual cortical hyperactivation in migraines. 
The cortex is generally hyperexcitable in migraines, and this hyperexcitability has been found to be the underlying mechanism of visual stress. Visual stress results from a hyper response to strong visual sensory stimulation that causes a spread of excitation through the visual cortex, leading to the inappropriate firing of neurons and resulting in perceptual illusions and distortions, that often promote a migraine attack.
The efficacy of precision ophthalmic tints in preventing migraine headache has been reported in several studies  showing the suppressing effect of the PCLs on visual cortical activity in MwA patients, suggesting a possible new prophylactic therapy for migraines. They are safe, free of side effects, and relatively inexpensive. While medications address the pain of migraines, precision tinted lenses reduce the triggers to the discomfort and distortions.