Aqueous humor ascorbic acid concentration

E, (Robertson et al. 1989), or B2 (Prchal et al. 1978) may be more susceptible to cataract formation in general. The concentration of ascorbic acid in the aqueous humor of adult animals is generally higher than that in young animals (Kinsey et al. 1945). Ascorbic acid concentration in the eyes of... 

The aqueous humor is characterized by a high ascorbic acid concentration, and addition of ascorbic acid to the medium of human trabecular meshwork cells in culture resulted in a significant dose-dependent stimulation of hyaluronan synthesis and secretion (26). 

Iwata S, Miyauchi S, Takehana M. Biochemical studies on the use of sodium hyaluronate in the anterior eye segment. I. Variation of protein and ascorbic acid concentration in rabbit aqueous humor. Curr Eye Res 1984 3 605-610... 

There must also be a second mechanism of ascorbic acid transport through certain specialized cells, difierent from the diffusion of dehydro-ascorbic acid followed by intracellular reduction. There are no indications that dehydroascorbic acid is involved in the renal tubular absorption of ascorbic acid, and, contrary to earlier conclusions, it appears that the concentration of ascorbic acid into the aqueous humors of the eye occurs in the form of ascorbic acid itself. 

It seems clear that ascorbic acid enters the eye as a constituent of aqueous humor. From there it can be shifted into the cells of the lens and also into the endothelial monolayer which lines the inner surface of the cornea. It is likely that some ascorbic acid diffuses from the aqueous humor into the vitreous cavity. However, McGahan (1985) suggested that ascorbic acid may also enter the vitreous humor from other sources perhaps some passes out of the retina. In most species, the concentration of ascorbic acid in the vitreous humor is the same as that in aqueous humor or slightly lower (DiMattio, 1989a McGahan, 1985 Varma and Richards, 1988). 

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