Fluorescence in human lens.

Abstract In human lens there are two major types of fluorescence, one of which is emitted around 340 nm when excited at 290 nm (purple fluorescence), and the other with activation and emission wavelength respectively in the neighborhood of 340 and 420 nm (blue fluorescence). The level of the purple fluorescence is high in comparison with that of the blue in all the protein fractions of the lens examined. In both fluorescence, urea soluble (U.S.) fraction of the insuluble protein shows the highest level, and gamma crystallin the lowest, whereas the level in alpha and beta crystallins is in between. The purple fluorescence of the human lens associated with both soluble and insoluble fraction seems to be maintained at a relatively constant level throughout life of human lens, while the blue fluorescence observed in both soluble and insoluble fractions increases with age. The age-related changes in the blue fluorescence is more conspicuous in the U.S. fraction than in the soluble proteins. It appears that the increase in lens fluorescence observed with age is attributed mainly to the blue fluorescence.