Distribution of aromatic and fluorescent compounds within single human lenses

The concentration of the free aromatic amino acids tryptophan and tyrosine, the antioxidant uric acid and some unidentified compounds have been determined in the water-soluble extracts of parts from clear and nuclear-cataractous human lenses. With age (29-90 years) and cataract formation, associated with increasing nuclear pigmentation, no significant changes were observed in content of tryptophan, tyrosine and uric acid. Furthermore, these compounds did not show variation in distribution within the lens. An unidentified fluorophore, excitation and emission maxima of 345 and 425 nm, respectively, increases significantly in content with nuclear cataract formation, especially in the nucleus. Another unidentified, presumably aromatic compound shows a striking age-related decrease.