Photographic and spectroscopic correlations of human cataracts

Intracapsular cataracts obtained within 3 h after surgical extraction were photographed with the CCRG technique and immediately subjected to fluorescence spectroscopy followed by 31P- and 13C-nuclear magnetic resonance (NMR) spectroscopy. Fluorescence spectroscopy demonstrates an excellent correlation between nontryptophan fluorescence intensities and lens color. An interesting correlation was also observed between the degree of light scatter as determined by the 290-nm excitation peak for intrinsic lens tryptophan fluorescence and the CCRG (photographic) appearance of these cataractous lenses. Based on 100 cataracts analyzed, there is a strong correlation between this kind of light scattering measurement and the type and degree of lens opacification. A similar correlation is evident with the 31P-NMR organophosphate profiles in the lenses in which the sugar phosphate levels are elevated only in diabetic patients with cataracts ('diabetic cataracts'). Aside from fluorescence and 31P-NMR spectroscopy, selected lenses were also incubated with 5.5 nM 13C-glucose as soon as they were obtained, and the foregoing spectroscopy was performed, followed by 13C-NMR analyses to detect and monitor for sorbitol accumulation in young versus old normal lenses and in diabetic cataracts. These studies clearly demonstrate a direct correlation between nontryptophan-fluorescent chromophore levels, light scattering (determined by tryptophan excitation peaks), lens age and cataract type. In addition, the organophosphate profiles clearly delineate the diabetic cataracts, and the 13C-NMR spectra correlate well with the age-related decrease in aldose reductase activity.