Lectures in optics ; volume 4: Visual optics This fourth volume of the series Lectures in Optics provides a comprehensive coverage of the field of Visual Optics which is the field of optics as it applies to the function of the eye. Itself the eye is a magnificent yet very complicated optical system. The optics part of vision in a well performing eye called an emmetropic eye pertains to the effects responsible for the formation and initial detection of the retinal image the picture of the world as it is projected on the photosensitive layer of the eye the retina. The book thoroughly presents the necessary concepts and definitions that explain the retinal image properties identifying the eye as an optical system that forms and detects this minified inverted and real image. Aspects of the definite properties such as visual acuity and color perception are also thoroughly presented The optics of the eye are affected by refractive errors and the effects of aging discussed in the second part of the book. Refractive errors such as myopia hyperopia and astigmatism and limitations such as accommodation and near vision are the main topics of this part alongside the effects of aging such as presbyopia and low vision. Finally the book concludes with an in depth presentation of the optics of the correction of these effects known as ophthalmic optics and prismatic effects