What causes Visual Stress
A simplified explanation of the causes
Visual Stress occurs when specific images trigger an overreaction in the brain leading to symptoms including physical and visual discomfort and vestibular and perceptual difficulties.
In simple terms, Visual Stress happens when lights, glare, contrast, patterns, movement, flicker, or colours cause the brain to overreact. This reaction can lead to many signs and symptoms, such as nausea, headaches, fatigue, or sensitivity to light and patterns, as well as difficulties with reading, attention, behaviour, and sensory processing.
Reviewing the Diagnostic Criteria will help to identify if Visual Stress is present and contributing to the symptoms.
A scientific theory of the causes
The most widely supported theory of Visual Stress explains that it results from a general overexcitation of the visual cortex caused by a hypersensitivity to contrast, pattern, or glare. The visual cortex normally works efficiently until stimulation is too strong and cortical processing becomes inefficient.
A neural mechanism for Visual Stress has found support in studies showing that the visual stimulus that induces discomfort also induces a significant hemodynamic response, both in absolute terms and relative to the reaction to comfortable stimuli. This response triggers neurons that signal movement, which is then experienced as illusions or hallucinations. [1]
For a detailed description of how the initial triggers progress into symptoms, visit the Visual Stress process page.
The severity
Research has identified a continuum of photosensitivity, for example, in people with photosensitive epilepsy, migraine, and Visual Stress. Individuals with photosensitive epilepsy or migraine may experience more extreme Visual Stress symptoms than someone without these conditions. [2]
It is important for people who suffer, or may suffer, from Visual Stress to identify other possible contributing factors and receive treatment for any related conditions.
Visual Stress falls on a continuum
How can a visually stressed brain be calmed?
With the use of colour! Colour filters help reduce the over-excitation of the brain, and it has been demonstrated using several brain-scanning techniques, including fMRI, in a study conducted at Michigan State University [3].
Research suggests that because a wavelength of light, particular to the individual, is known to affect neuronal sensitivity, the use of colour filters, also particular to the individual, could reduce over-excitation, redistributing cortical hyperexcitability and, thus, reducing perceptual distortion and headaches.
Colour filters, in the form of precision tinted lenses and coloured overlays, have been identified as effective and practical tools and solutions for reducing the visual triggers to discomfort and other Visual Stress symptoms.
Sources
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Wilkins A., A physiological basis for visual discomfort: application in lighting design. Lighting Res Technol. 2016; 48:44---54 https://journals.sagepub.com/doi/pdf/10.1177/1477153515612526
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Wilkins A., Physiology of Human Photosensitivity. Epilepsia: https://onlinelibrary.wiley.com/doi/full/10.1111/j.0013-9580.2004.451009.x
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Huang, J et al., fMRI evidence that precision ophthalmic tints reduce cortical hyperactivation in migraine. Cephalalgia: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3132147/
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