A broad-ranging textbook describing the physical principles upon which modern ophthalmic technology is based. With clear text and diagrams, the book covers the physics of medical imaging and electrosurgery and provides in-depth and up-to-date coverage of automated assessment of vision. For ease of use, mathematical formulae are used sparingly and the principles are also described in words - no background in physics is assumed. It should help the reader gain a better understanding of the technological side of the field and can be used as a course book for the Optics and Refraction module of the Fellowship of the Royal College of Ophthalmologists and similar exams.