Vascular changes that occur in the human retina and choroid have frequently been studied through the use of light microscopy. This technique has marked limitations, however, in that it shows changes only in limited localized sites, often with the effects of various systemic diseases indistinguishable. Newer techniques of corrosion cast scanning electron microscopy and transmission electron microscopy provide a much clearer three-dimensional view of retinal and choroidal vasculatures, the results of which will be useful for the interpretation of ocular fundus changes seen in individual systemic diseases. Retinal and choroidal vascular changes due to aging, arteriosclerosis, spontaneous hypertension, and diabetes mellitus in the rat have been investigated and are described in this book, which will be of interest to those in the fields of ophthalmology, anatomy, and pathology. This book is a leading source of information on the use of electron microscopy in a new field of interest. .