Equal accessibility to public places and services is now required by law in many countries. For the vision-impaired, specialised technology can provide a fuller enjoyment of the facilities of society, from meetings and public entertainments to reading a book or making music. This volume explores engineering and design principles and techniques used in assistive technology for blind and vision-impaired people. Features include instruction in the physiology of the human visual system and methods of measuring visual ability; explanation of electrical engineering principles of devices designed for everyday living; practical projects and investigations which inspire student work and self teaching; contributions by renowned authors from diverse fields under the banner of assistive technology: artificial vision, psychology, haptics, electrical engineering, design and visual physiology. This book is a source of reference for professionals who develop devices and services for people with sight loss, and for students working in assistive technology and rehabilitation.