Change in Diameter of the Larger Retinal Vessels after Different Stimuli in Normal

SYSTEMIC DISORDERS often cause pathological changes in the optic fundus. These changes have diagnostic value because of their empirical association with specific illnesses. The value of funduscopic examination would be even further increased by a better understanding of how certain of these fundic lesions are produced. With the ultimate object of investigating this problem, several photographic techniques for study of the retinal circulation and metabolism in man have been adapted or developed and used by the authors and their associates. These techniques are: (1) measurement by fundus photography of changes in the diameter of retinal vessels in response to various stimuli, a procedure previously used by others;" 2 (2) estimation by fundus photography of the arteriovenous blood oxygen difference, (3) a method of photographing fluorescence in circulating blood in the retina, and (4) a method for measuring the mean retinal circulation time using fluorescein. It is the purpose of this presentation to summarize some results obtained by these special techniques and to interpret them in relation to the work of others in this rapidly expanding field.