Many children experience symptoms of Visual Stress when reading. This includes distortions in text and eye strain. Using a coloured overlay on the reading material has proven to reduce these symptoms and increase reading speed in individuals with photosensitive epilepsy and autism. Tourette syndrome (TS) and autism often clinically overlap and individuals with autism have shown similar symptoms observed in those suffering from Visual Stress.
In 2013, a researcher, from the Anglia Ruskin University’s Psychology Department, conducted a pilot study  to investigate the effects of coloured overlays in children with TS. The pilot study indicated that a substantially large proportion of children with Tourette syndrome may suffer from Visual Stress when reading. Coloured overlays appeared to help remediate these symptoms and improve reading rate.
Based on these findings, a larger controlled study was completed and the results were published in 2016.  The report notes that if Visual Stress and sensory difficulties are related problems, then the prevalence of Visual Stress is likely to be higher in children with sensory disorders such as TS. Eighty percent of individuals with Tourette syndrome reported that "tics" were produced as intentional responses to aversive sensory phenomena and some researchers have even speculated that TS is characterized by a hypersensitivity to sensory stimulation. Given the overlap between sensory behaviours, hypersensitivity and Visual Stress, it seems likely that Visual Stress may be contributing to symptoms in Tourette.
The study found that an abnormally higher proportion of the children with TS read more quickly with the use of a coloured overlay, with levels of improvement reaching up to 54%. The results of this study provide further evidence consistent with an association between sensory difficulties and cortical hyperexcitability and suggests that children who are hypersensitive, to sensory stimuli may experience great benefits from the use of a colour filter.
Given that coloured filters have been found to benefit performance on tasks other than reading, including matching to sample, visual search and recognition of emotions. The overlays might offer an important tool for children with sensory disorders in educational settings.
Tourette's syndrome (TS)