In situ fluorescence spectroscopic studies on bovine cornea

The cornea is a transparent ocular tissue and its transparency is thought to be a result of intramolecular interactions and the supramolecular organization of its protein constituents. We have studied the intrinsic fluorescence properties of intact bovine corneas and compared these with that of the opaque sclera. It was observed that with increasing excitation wavelengths the emission maxima shifted toward the red edge exhibiting the phenomenon of red edge excitation shift, which is indicative of immobilization of the constituent fluorophores. The magnitude of the shift increased after photodamage by irradiation at 295 nm. Many of the spectral characteristics of the cornea are shown to be due to its proteoglycans, which show surprisingly significant red edge excitation shift in solution.