Abstract: An apparatus is disclosed for using quasielastic light scattering to determine the degree of cataractogenesis of a lens in vivo. By collecting and analyzing light scattered from the lens, it is possible, using the temporal autocorrelation function, to produce a signature of cataractogenesis, accounting for scattering due to immobile scatterers. The components of the cataractogenesis can also be detected by comparing the values of the components of the signature of cataractogenesis to frequency distribution of the components taken from populations or by detecting changes in the values of the components of the signature of cataractogenesis as a function of time.