Distribution of two metabolically related fluorophors in human lens measured by laser microprobe.

Automated Raman microprobe spectrometry revealed the distribution of a major fluorophor, 3-OH-L-kynurenine-O-beta-glucoside, in human lenses from 0.38 to 71 yr. A three-dimensional perspective grid map with fluorescence intensity as the third dimension shows maximum fluorescence in the infant lens nucleus. At 12 yr the fluorescence peak is broadened and a toroid-shaped maximum occurs also in the outer cortex, creating a toroid-shaped minimum between the two maxima. By 71 yr the nuclear maximum is lower but a new (green) fluorophor (excitation 488 nm: emission 530 nm) has appeared as a toroidal maximum in the same location as the blue minimum, suggesting the conversion of the blue fluorophor to the unidentified green fluorophor.