Study of fluorescein glucuronide. I. Isolation from urine

The loss of fluorescein, fluorescein glucuronide and fluorescein isothiocyanate dextran from the vitreous by the anterior and retinal pathways

The pathways by which fluorescein (F), fluorescein glucuronide (FG) and fluorescein dextran (FD) leave the vitreous body of the rabbit were examined by measuring the concentration distribution of the injected fluorophores in sections of the frozen eyes. The contours of F, as already known, show that it leaves the vitreous predominantly across the retinal surface. Mathematical analysis of the concentration gradient leads to an average outward permeability coefficient of 1.4 x 10(-3) cm min-1 for the retinal layers. The contours of FG and FD show that they leave predominantly by diffusion into the posterior chamber, encountering only a minor barrier at the anterior hyaloid membrane. The anterior contours indicate that there can be no substantial posteriorly directed fluid flow through the vitreous; if it occurs its velocity across the retinal surface must be less than 2 x 10(-5) cm min-1. The contours of FD near the posterior pole of the retina suggest that such a flow may be taking place. Some time after the systemic administration of F, an analysis of the rate of loss of fluorescence from the vitreous body shows that this corresponds to the movement of FG out through the anterior chamber. Its value bears little relationship to the condition of the blood-vitreal barrier.

Plasma fluorescein and fluorescein glucuronide in patients with selected eye diseases

Systemically administered fluorescein (F) is rapidly transformed to the fluorescent metabolite fluorescein glucuronide (FG). Little is known about how diseases can influence the synthesis or disposition of FG. We studied F and FG in the plasma ultrafiltrate of 75 people who were normal or had diabetes, retinitis pigmentosa, or idiopathic rhegmatogenous retinal detachment. F and FG were determined by high-performance liquid chromatography. The concentration of FG was comparable to F 1 h after an intravenous injection of F, both in normal subjects and in patients with retinitis pigmentosa, which suggests that FG may not be an important contributor to the vitreous fluorescence at that time. At later times FG substantially exceeded F. The concentration of FG was significantly higher in diabetics than in the other groups 14 h after an oral dose of F. Accordingly, the possible effect of disease on plasma dye concentrations should be considered in studies measuring F by fluorescence hours after systemic F administration, since this could influence the intraocular fluorescence irrespective of any alteration in ocular function.