Visual Stress is a distinct condition to Dyslexia. Those with Visual Stress report that words appear to move, wobble or flicker when they read for any length of time, or that they perceive colours or other illusory phenomena in the background to the text. These symptoms can affect reading fluency and cause eye strain, headaches or even migraines. If looking at text is not comfortable, children will tend to avoid reading, which in turn can slow the development of reading skills.
The condition is thought to be caused by overactivity of cells in the part of the brain that process information from the eyes. For reasons that are not well understood, the symptoms of Visual Stress can often be reduced by changing the background colour of the text using an overlay or coloured lenses. The colour which minimises symptoms varies from one person to the next, hence a range of colours are required.