Services for Developmental Dyslexia in Hong Kong

The Greek prefix dys refers to difficult or hard, and lexia refers to words. Dyslexia characterises significant word recognition and spelling difficulties in affected individuals. It is one of several distinct specific learning disabilities, in contrast to the more general terms Specific Disabilities (SLD) or Learning Disabilities (LD) used to describe larger sets of individuals with listening, speaking, reading, writing and mathematics difficulties. Epidemiological studies show that dyslexia constitutes at least 80% of the SLD/LD population; and because of its long lasting effects, it has an important impact on public health. This definition which draws from the relationship of biological and psychological underpinnings with behaviour, is in contrast with both the International Classification of Diseases ICD-10 2 and DSM-IV, 3 which apply operationalised criteria in their definitions of a reading disability. The National Institute for Child Health and Development of the United States reported an approximate prevalence rate of 10% of school-aged children being affected to varying degrees, with 3-5% estimated to be severely affected.