Much has been discovered in recent years about the way our visual system copes with very low light levels, and this detailed up-to-date book describes the light and dark adaptation of receptoral and post-receptoral mechanisms from a number of perspectives. The authors emphasize the importance of the study of achromatosia, a rare congenital condition in which the visual mechanisms that mediate day vision are absent while those that mediate night vision remain intact, in isolating those parts of the visual apparatus that are normally associated with night vision. In addition, there is a comprehensive review of ocular conditions that involve a loss of night vision. The final section of the book discusses various types of nightviewing instruments presently available, against the backdrop of what limits night vision in normal observers. Contributions from many of the world's leading experts in vision research makes this unique volume essential reading for all those interested in vision, including opthamologists, optometrists, neurologists, physiologists and psychologists.