Lack of attention’ span is not necessarily accompanied by dyslexia; each one of them is to be diagnosed separately. However, research has proved that some dyslexic persons also suffer from a lack of attention or hyperactivity disorders. It is certain that attention disorders disrupt reading development; they may appear through slowness due to multiple hesitations or a high tension tendency interfering  during the reading process. Photosensitivity (light sensitivity): a limited number of dyslexic persons (between 3 to 8 %) suffer also from photosensitivity. Some of them hardly distinguish little printed characters in black on a white sheet of paper and have the impression that these characters move or shake slightly, while others tend to dislike fluorescent lighting and to hide their paper by their hand or head while reading.