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. .

Retinal and choroidal vasculatures are easily affected by various systemic diseases, and changes in the retina can easily be observed with various procedures such as direct and indirect ophthalmoscopy, scanning laser ophthalmoscopy, fluorescein fundus angiography, and indocyanin green fundus angiography. Vascular changes are the major, most prominent, and most important fundus changes. The above-mentioned procedures can reveal vascular changes clearly, but mainly reveal changes in the superficial layer of the retina. In addition, these procedures cannot show the three-dimensional architecture of the retina. Usually we can barely obtain the view of that three dimensional architecture. At the same time, pathological findings are well described, but most of them are based on histological and cytological methods. Thus, three-dimensional description of pathology is rare. Vascular corrosion cast scanning electron microscopy can provide a very useful three-dimensional view of the microvasculature and can demonstrate the fine structural architecture of the capillary network. However, the application of this method to the retinal and choroidal vasculature is very difficult, especially in small eyes. We succeeded in making good corrosion casts of retinal and choroidal vessels in the rat. Using this method during the past 10 years we have examined the retinal and choroidal vascular architecture of rats with various systemic diseases such as aging, hypertension, diabetes mellitus, and arteriosclerosis."