fMRI evidence that precision ophthalmic tints reduce cortical hyperactivation in migraine

Abstract

Background Certain patterns can induce perceptual illusions/distortions and visual discomfort in most people, headaches in patients with migraine, and seizures in patients with photosensitive epilepsy. Visual stimuli are common triggers for migraine attacks, possibly because of a hyperexcitability of the visual cortex shown in patients with migraine. Precision ophthalmic tints (POTs) are claimed to reduce perceptual distortions and visual discomfort and to prevent migraine headaches in some patients. We report an fMRI visual cortical activation study designed to investigate neurological mechanisms for the beneficial effects of POTs in migraine. Methods Eleven migraineurs and 11 age- and sex-matched non-headache controls participated in the study using non-stressful and stressful striped patterns viewed through gray, POT, and control coloured lenses. Results For all lenses, controls and migraineurs did not differ in their response to the non-stressful patterns. When the migraineurs wore gray lenses or control coloured lenses, the stressful pattern resulted in activation that was greater than in the controls. There was also an absence of the characteristic low-pass spatial frequency (SF) tuning in extrastriate visual areas. When POTs were worn, however, both cortical activation and SF tuning were normalized. Both when observing the stressful pattern and under more typical viewing conditions, the POTs reduced visual discomfort more than either of the other two lenses. Conclusion The normalization of cortical activation and SF tuning in the migraineurs by POTs suggests a neurological basis for the therapeutic effect of these lenses in reducing visual cortical hyperactivation in migraine.

A physiological basis for visual discomfort: Application in lighting design

“…There are large individual differences in people's preference for the colour of lighting, and these individual differences have a neurological basis. Huang et al 29 asked patients with migraine to observe text in an apparatus that permitted the separate control of the hue, saturation and luminance of the illuminating light. They selected a chromaticity that optimised the visual comfort of the page.…”

Accommodation to Uncomfortable Patterns

“…When the discomfort is reduced by the use of tinted ophthalmic lenses, the cortical response is 'normalised'; that is, the migraineurs then show a similar cortical response to controls (Huang et al, 2011;Coutts et al, 2012). The experiments reported here suggest that the heightened cortical response to the uncomfortable patterns is not dependent on poor accommodation.…”

Increased Vulnerability to Pattern-Related Visual Stress in Myalgic Encephalomyelitis

“…For example, although visual stress is suggested to infer reduced inhibitory and/or increased excitatory neurotransmission in visual cortex (e.g. Beasley & Davies, 2012, Huang et al, 2011, Wilkins, et al, 2004, the present study did not assess this directly. However, it is of note that this account of visual stress does fit well with the notion that more general aspects of ME/CFS might be understood, in part, within the context of abnormal neurotransmitter activity throughout the brain (Jason et al, 2011).…”