Scotopic Sensitivity Syndrome

A perceptual processing condition in which the brain has difficulty handling certain visual information, particularly high-contrast patterns like black text on a bright white background. People with scotopic sensitivity may experience text appearing to move, shimmer, or blur on the page; eye strain and fatigue; difficulty tracking lines of text; and headaches during reading. A significant fraction of people with dyslexia also experience scotopic sensitivity. For web accessibility, this condition supports recommendations to avoid pure white backgrounds (using off-white or cream colours like #FFFFE5 instead), to provide user-customisable colour schemes, and to avoid high-contrast black-on-white text. Coloured overlay filters and tinted lenses are common accommodations.