The book describes the mechanism of vision initiated by photo-transduction, through a biochemical cascade that regulates the activity of ion channels in the membrane of the photoreceptor's outer segment, and thereby the number of neurotransmitters the photoreceptor releases. The signal sent to the visual centers in the brain is highly processed when it leaves the retina, emphasizing those aspects of the visual scene that convey the most significant information. Adaptation to light & dark is discussed. The most common Human Eye Diseases are mentioned with emphasize on the major alterations of the retinal tissue.