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Corneal epithelium and UV-protection of the eye
1University Eye Department, National Hospital Oslo, Norway.
Purpose:
To study UV-absorption and UV-induced fluorescence in the bovine corneal epithelium.
Methods:
Spectrophotometry and spectrofluorimetry.
Results:
The corneal epithelium absorbs UV-B radiation mainly owing to its content of protein, RNA, and ascorbate. Some of the absorbed energy is transformed to the less biotoxic UV-A radiation by fluorescence. RNA and ascorbate reduce tissue fluorescence.
Conclusions:
The corneal epithelium acts as a UV-filter, protecting internal eye structures through three different mechanisms: (1) Absorption of UV-B roughly below 310 nm wavelength. (2) Fluorescence-mediated ray transformation to longer wavelengths. (3) Fluorescence reduction. The extremely high ascorbate concentration in the corneal epithelium has a key role in two of these processes.