Page:A manual and atlas of medical ophthalmoscopy.djvu/17



ophthalmoscope is of use to the physician because it gives information, often not otherwise obtainable, regarding the existence or nature of disease elsewhere than in the eye. The characters of the changes which possess this general significance, and of the special alterations in the fundus oculi in individual diseases which come under the physician's care, constitute the subject of the following pages.

The information furnished by the ophthalmoscope depends upon the circumstance that we have under observation—1. The termination of an artery and the commencement of a vein, and the blood circulating within them. 2. The termination of a nerve, which, from its close proximity to the brain, and from other circumstances, possesses significant relations to the rest of the nervous system. 3. A nervous structure—the retina, which suffers in a peculiar way in many general diseases. 4. A vascular structure—the choroid, which also presents changes in certain constitutional affections.

For the efficient use of the ophthalmoscope in medical practice, the student must be familiar, first, with the use of the instrument; and, secondly, with the normal fundus oculi, with the changes in its appearance (congenital, &c.) which are of no significance, and also with those which are of purely ocular significance, such as posterior staphyloma, glaucomatous