Optics is the study of the behaviour and properties of light. A refraction test is given as part of a routine eye examination. The test tells an optometrist what prescription is needed in glasses or contact lenses. The new edition of this book is a comprehensive guide to the optics of the human eye and various errors of refraction, including their clinical presentation and management. Divided into eleven chapters, the text extensively covers the physical properties of light, reflection and refraction, curved optical devices, optics of the normal eye and errors of refraction, devices for optical examination, contact lenses, low vision aids, and refractive surgery. The second edition has been fully revised and updated to provide clinicians and trainees with a thorough understanding of the latest advances and technologies in the field.