A method has been developed for the quantitation and documentation of optical changes of the lens that occur with aging and cataract formation. The method is based on quantitative measurements of the back scatter of light from defined regions of the in vivo human lens using a slitlamp camera and microdensitometric analyses of the resulting negatives. Examination of a group of normal patients and patients with nuclear sclerosis and senile cataract indicates the following conclusions: (1) Back scatter of light increases with aging of the in vivo lens. (2) The nuclear region of the young lens has insignificant back scatter of light but such scattering increases with aging. (3) The cortex causes appreciable back scatter in young lenses. There is a slight increase in this back scatter with age which appears to be caused primarily by the growth of the cortical region rather than changes in already existing cortex. (4) The eye appears capable of tolerating considerable back scatter without loss of visual acuity. (5) In nuclear senile cataract large increases in the back scatter of the nuclear region can be observed.
Sigelman J, Trokel SL, Spector A. Quantitative Biomicroscopy of Lens Light Back ScatterChanges in Aging and Opacification. Arch Ophthalmol. 1974;92(5):437-442. doi:10.1001/archopht.1974.01010010449016