Normal and Impaired Retinal Vascular Reactivity

Normal retinal arteries and veins will constrict when the arterial blood oxygen tension is increased and dilate when it is lowered. A technic, employing fundus photography, is described for measuring this reaction. The amount of constriction on breathing oxygen, and its trend with age, have been measured in normal subjects. The arteries of persons with well-established hypertension and diabetes usually show marked impairment of this constrictor reaction, presumably because of sclerotic changes. It is suggested that measurements of this reaction may prove to be a useful, quantitative extension of present retinal vascular grading technics.