FLUORESCENCE PROPERTIES OF ISOLATED INTACT NORMAL HUMAN CORNEAS

We have examined the fluorescence properties of excised intact normal human corneas from over a hundred donors, using synchronous excitation fluorescence spectroscopy. In some of the corneas from the donors, a fluorophore with an excitation band centered at 330 nm was observed. T his fluorophore does not seem to correspond to the dityrosine moiety o r to any photoproducts of tryptophan. Isolated corneas irradiated with light of 295 mm wavelength do not produce any fluorescent photoproduc ts, suggesting that the intact tissue has endogenous quenchers, radica l scavengers and antioxidants that inhibit its photodamage. The non-tr yptophan fluorophores that accumulate in some corneas thus appear to a rise largely from the nonenzymatic glycosylation (glycation) of the co nstituent proteins as similar fluorophores are detected in the corneas of rats in which diabetes is induced.