Equal accessibility to public places and services is now required by law in many countries. For the vision-impaired, specialised technology often can provide a fuller enjoyment of the facilities of society, from large scale meetings and public entertainments to reading a book or making music. This volume explores the engineering and design principles and techniques used in assistive technology for blind and vision-impaired people. This book maintains the currency of knowledge for engineers and health workers who develop devices and services for people with sight loss, and is an excellent source of reference for students of assistive technology and rehabilitation.