Book excerpt: This book provides a practical, clinical approach appropriate to a subject of increasing importance in an aging population. It contains a survey of the causes, types, manifestations and incidence of partial sight or low visual acuity. Detailed consideration is given to the examination and assessment of visually impaired adults and children. The author describes the importance of lighting, color contrast and other non-optical aids to vision and discusses the advisory role that the optometrist can play in helping the patient make the best use of residual vision.