Hematocrit and blood content in the rabbit eye

The red blood cell volume and the apparent plasma volume in the ocular tissues of the rabbit were measured using 51Cr labelled red blood cells and 125I labelled human serum albumin. On this basis, the hematocrit of the circulating blood in the eye and the blood content in the ocular tissues were estimated. In the retinal circulation, the hematocrit was 26, which was 70% of the hematocrit of the cardiac blood. This value was thought to be also applicable in the uveal tissue, although the extravascular leakage of the tracer albumin did not allow an exact determination of the hematocrit of the circulating blood in this tissue. The blood content per 1 gram tissue was calculated from the red blood cell volume and the hematocrit determined. It was about 63 microliter in the iris, 59 microliter in the ciliary body, 198 microliter in the choroid and 38 microliter in the retina. The value obtained in the iris or ciliary body was similar to that in the cardiac muscle or intestine, and the value in the choroid was similar to that in the kidney, lung or liver. The value in the retina was greater than that reported in the brain.