Many times when someone thinks of dyslexia they think of someone reading backwards. Dyslexia is NOT simply reading backwards.
Dyslexia is a specific learning disability that is neurological in origin. It is characterized by difficulties with accurate and or/fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge.
(adopted by the International Dyslexia Association Board of Directors, Nov. 12, 2002)
Scientists can actually see a dyslexic person's brain at work using fMRI and asking them to perform a task! Dyslexic people read using a different area of their brain.