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Visual Stress and Coloured Overlays
What is Visual Stress?
Visual stress (sometimes called ‘Meares-Irlen Syndrome’ or ‘Scotopic Sensitivity Syndrome’) is the experience of unpleasant visual symptoms when reading, especially for prolonged periods. Symptoms include illusions of shape, movement and colour in the text, distortions of the print, loss of print clarity, and general visual irritation. Visual stress can also cause sore eyes, headaches, frequent loss of place when reading, and impaired comprehension. Visual stress is caused by the striped effect of black writing on white paper which causes over stimulation and excitation of the visual cortex.
The condition of visual stress was first discovered independently by Olive Meares, a teacher in New Zealand, in 1980, and by Helen Irlen, a psychologist in the United States in 1983.