Approximately 20% of the population experience discomfort when looking at certain patterns- including rows of text. In the most severe cases, symptoms can include headaches, migraines or even seizures. More commonly, the text can appear to move wobble or flicker making it difficult to read fluently. This is known as Visual Stress.

Visual Stress is thought to be caused by overactivity of certain groups of cells in the visual areas of the brain. The good news is that the symptoms can often be reduced by using a coloured overlay, coloured lenses or by changing the background colour of the screen or tablet that you are looking at.