This title is directed primarily towards health care professionals outside of the United States. The fourth edition of this classic textbook has been brought thoroughly up to date with revised chapters on Ocular Aberrations, Visual Examination of the Eye, and Distribution and Ocular Dioptics of Ametropia. New contributors have been added and the book has been completely redesigned using colour to offer a more accessible layout and enhance the many line illustrations. The new companion website has valuable additional resources including a simulation of subjective refraction, video clips showing clinical procedures and extra appendices to the book.