Distribution of ascorbate in the anterior bovine eye

PURPOSE. To analyze the ascorbate distribution ill the anterior eye wall to better understand the functional significance of this compound in the eye. METHODS. Ascorbic acid was determined by high-performance liquid chromatogr aphy using an LC-10 system (Shimadzu, Kyoto, Japan). Bovine eye samples wer e used. RESULTS. The highest ascorbate concentration was observed in the corneal ep ithelium, with significantly higher values in the central (1.56 mg/g) than in the peripheral (1.39 mg/g) area. The ascorbate content was similar in th e corneal stroma (0.22 mg/g), the Descemet's membrane (DM)/endothelium (0.2 2 mg/g), and the aqueous humor (0.21 mg/ml). By comparison, the sclera (0.1 5 mg/g) and the conjunctiva (0.11 mg/g) showed lower values, as did the lac rimal gland (0.09 mg/g) and the serum (0.0008 mg/ml). CONCLUSIONS. (1) Peak ascorbate concentration was observed in the central c orneal epithelium covering the pupillary area. This is compatible with the idea that the ascorbate may act as an UV filter shielding internal eye stru ctures from radiation damage. (2) The ascorbate concentration in the cornea l stroma and DM/endothelium was as high as in the aqueous humor, and it is suggested that the aqueous humor plays a key role in the distribution of as corbate to the anterior eye wall.