Why do some people move their heads back and forth when they are reading?

If you have to move your head to follow the text when you read your ocular motilities may be deficient. When the six eye muscles in each eye move efficiently in coordination with each other, they can make very fine eye movements. The muscles coordinate to point the eyeballs to keep a visual image near and single. People who use their neck muscles to point their eyes don't realize this- it isn't a conscious failure, though. These people may have deficits of their saccadic eye movements, the short little hops that the eyes make from the end of one word or line of text to the beginning of the next. These same individuals may find it helpful to use a straight edge to keep their place while reading. They may also experience frequent loses of place and may habitually skip little words or even whole lines of text. Developmental optometrists often incorporate vision therapy in their practices. Simple activities and exercises can often promote the development of great saccadic eye movements over a period of several weeks.