A systematic review of controlled trials on visual stress using Intuitive Overlays or the Intuitive Colorimeter

摘要

Claims that coloured filters aid reading date back 200 years and remain controversial.udSome claims, for example, that more than 10% of the general population and 50% of people withuddyslexia would benefit from coloured filters lack sound evidence and face validity. Publicationsudwith such claims typically cite research using methods that have not been described in theudscientific literature and lack a sound aetiological framework.udNotwithstanding these criticisms, some researchers have used more rigorous selection criteriaudand methods of prescribing coloured filters that were developed at a UK Medical ResearchudCouncil unit and which have been fully described in the scientific literature. We review thisudresearch and disconfirm many of the more extreme claims surrounding this topic. This literatureudindicates that a minority subset of dyslexics (circa 20%) may have a condition described asudvisual stress which most likely results from a hyperexcitability of the visual cortex. Visual stressudis characterised by symptoms of visual perceptual distortions, headaches, and eyestrain whenudviewing repetitive patterns, including lines of text. This review indicates that visual stress is distinctudfrom, although sometimes co-occurs with, dyslexia. Individually prescribed coloured filtersudhave been shown to improve reading performance in people with visual stress, but are unlikelyudto influence the phonological and memory deficits associated with dyslexia and therefore areudnot a treatment for dyslexia.udThis review concludes that larger and rigorous randomised controlled trials of interventionsudfor visual stress are required. Improvements in the diagnosis of the condition are also a priority.