Retinal and Choroidal Blood flow Determined with Krypton-85 Anesthetized Animals

¹ Howe Laboratory of Ophthalmology, Harvard University Medical School and Eye Pathology Laboratory, Massachusetts Eye and Ear Infirmary, and Massachusetts General Hospital, Boston, Mass.

A method has been described for the estimation, by means of krypton-85, of the rate of nutrient blood flow to the retina of anesthetized animals. The isotope was injected into the carotid artery, and a multiexponential decay curve was obtained by transscleral monitoring with a small Geiger-Müller tube. Under the conditions of the experiment the average total retinal blood flow (in the choriocapillaris and the retinal vessels of the cat) was 510 ml. per 100 Gm. per minute. Evidence has been presented which indicates that the rate of flow of blood in the choriocapillaris was 1,200 ml. per 100 Gm. per minute, and that the flow of blood in the retinal vessels was 166 ml. per 100 Gm. per minute. Approximately 73 per cent of the radioactivity was distributed initially to the choriocapillaris and 22 per cent to the retinal vessels.