Abstract
Ttcenty-day-old male rats were fed on a diet containing 40 per cent galactose. Freeze-dried sections of cataractous and control lenses were studied by quantitative microradiographtj. During cataract development the protein concentration decreased in the cortex and, at early stages of cataract, also in the nucleus. In lenses with a distinct nuclear cataract, however, the lens nucleus had about the same high protein concentration as that in the controls. At this stage of cataract there tvas a great difference in protein concentration between the central and the peripheral lens regions, presumably partly because of changes in the concentrations of didcitol and electrolytes. The zone between the cortex and the nucleus had a steep protein gradient and contained irregular interfaces separating regions toith different refractive indices. The nuclear cataract may be explained by reflection of light at these interfaces. Scattering of light from the vacuoles in the cortex, most prominent at the early stage of cataract, is discussed. Other scattering processes in the cortex are also considered.