Dyslexia is an impairment of the ability to read, as a result of a variety of pathologic conditions, some of which are associated with the central nervous system.

Dyslexic persons often reverse letters and words, cannot adequately distinguish the letter sequences in written words, and have difficulty in understanding left from right.

Some reading experts doubt that dyslexia is a pathologic disorder and believe the condition represents a combination of reading problems, each of which should be...