STUDIES ON THE INTRA-OCULAR FLUIDS: 2. The Penetration of Certain Ions into the Aqueous Humour and Vitreous Body

Abstract

Rates of penetration of ions into the aqueous and into the vitreous are expressed in the form of parameters calculated from a known formula. Radioactive tracers were employed and their concns. measured with a Geiger counter technique, except for thiocya-nate, which was detd. colorimetrically. The rate of penetration of thiocyanate into the aqueous is greater than the rates of Na or K, and these, in turn, exceed the rate of phosphate. The entry into the vitreous of thiocyanate is 2 times, of Na 5 times, of K 3.5 times, and of phosphate 16 times, as slow as that of each corresponding substance into the aqueous. Thiocyanate appears to diffuse into the vitreous from all the surrounding vascular tissues, but Na and K penetrate into the vitreous predominantly from the ciliary region. These relative ratios of penetration of different ions bear no relationship to their ionic mobilities, and it appears that their transference from the blood to the chambers of the eye occurs through the cell bodies and not through the intercellular spaces. The plasma-vitreous barrier appears more selective than the plasm a-aqueous barrier.