Compartmentation of redox metabolites in the anterior eye segment?

In bovine corneal epithelium, stroma, and aqueous humor the levels of ascorbic acid (ASC) and dehydroascorbic acid (DHA) were investigated. Two methods were used, the photometric assay with 2,6-dichlorophenolindophenol and the formation of osazone by 2,4-dinitrophenylhydrazine. The ASC levels in the corneal epithelium and aqueous humor were found to be in the millimolar range, the ASC/DHA ratio being about 10. The stromal ASC and DHA levels were much lower, with a ratio of 0.7. ASC and DHA had similar levels and ratios to those of reduced and oxidized glutathione (GSH/GSSG) reported in the literature. In the corneal epithelium the redox ratio of glutathione was higher than that of ascorbic acid. Therefore, glutathione was supposed to reduce dehydroascorbic acid.