Identification of the scattering elements responsible for lens opacification in cold cataracts.

Using both quasi-elastic light scattering spectroscopy and angular dissymmetry in the intensity of the scattered light, we examined the onset of turbidity for intact calf lenses and for isolated nuclear cytoplasm. In the case of the nuclear cytoplasm these measurements demonstrate the presence of two kinds of scatterers: small units of approximately 100-A radius and larger elements whose size is distributed around 1,500 A. As the temperature is decreased towards the cold cataract temperature, the intensity of light scattered by the small units stays almost constant while the intensity scattered by the large elements increase very strongly. The opacification of the lens cytoplasm produced by decreasing the temperature results principally from an increase in the concentration of the large scattering elements. For the intact nucleus the situation is qualitatively similar, but the mean size of the large scattering elements shows a more substantial increase than in the isolated cytoplasm as temperature is lowered towards the cold cataract temperature.