Estimation of retinal blood flow in animals.

The applicability of the krypton-85 (Kr) clearance method to the study of retinal blood flow in cats, rabbits, and monkeys is discussed. Kr disappearance curves are found to be the same whether the isotope is injected via the common carotid artery or via the lateral long posterior ciliary artery. Kr disappearance curves are found to be similar whether the radioactivity is monitored with a Geiger-Muller (beta) probe, a solid state (beta) probe, or a scintillation (gamma) probe. Using the initial slope method of analyzing the Kr disappearance curves, the average rate of blood -flow to the retina (from choroidal and retinal vessels) is estimated at 800 ml. per 100 Gm. of retinal tissue per minute.