Symptoms of visual discomfort from automobile lights and their correlation with headache in night-time taxi drivers

This study examined how modern vehicle lights affect night-time taxi drivers and the relationships any effects have with headache. Sixty-eight drivers were asked about their perception of flicker, blurring, seeing double, smearing, glare, blinding, unease, discomfort, pain and headache/migraine from vehicle lights when driving at night. Participants were asked specifically about light emitting diodes, but responses may have included their experiences with other vehicle light types. Glare was the greatest problem, and red braking lights were worse than white lights around headlights. The headache group experienced greater problems, particularly for discomfort, pain, unease, flickering, seeing double and triggered headaches. Further research is needed as these effects pose potentially dangerous scenarios for all night-time road users, especially given the increased use of bright, directional light emitting diodes on vehicles and on roadsides

Visual processing in migraine

Background Migraine is a common neurological condition that often involves differences in visual processing. These sensory processing differences provide important information about the underlying causes of the condition, and for the development of treatments. Review of psychophysical literature Psychophysical experiments have shown consistent impairments in contrast sensitivity, orientation acuity, and the perception of global form and motion. They have also established that the addition of task-irrelevant visual noise has a greater effect, and that surround suppression, masking and adaptation are all stronger in migraine. Theoretical signal processing model We propose utilising an established model of visual processing, based on signal processing theory, to account for the behavioural differences seen in migraine. This has the advantage of precision and clarity, and generating clear, falsifiable predictions. Conclusion Increased effects of noise and differences in excitation and inhibition can account for the differences in migraine visual perception. Consolidating existing research and creating a unified, defined theoretical account is needed to better understand the disorder

Visual system dysfunction in migraine: a review of clinical and psychophysical findings.

This paper reviews both clinical and experimental literature relating to visual dysfunction in migraine, starting with the eye and progressing via the retina and visual pathways to the visual cortex. Migraine is associated with (i) a pupillary sympathetic hypofunction, and (ii) a cortical hypersensitivity to visual stimuli (perhaps only in migraine with aura), the pathogenesis of which remains to be determined. Various hypotheses are discussed, and it is proposed that the methods of visual psychophysics may represent a useful approach in the future study of cortical hyperexcitability in migraine. Paradoxically, little research has been directed towards understanding (i) the photophobia of migraine attacks, and (ii) how migraine may be triggered by visual stimuli. Research aimed at elucidating the mechanisms of these phenomena may enhance understanding of the pathogenes is of migraine