Light scattering and reversible cataracts in the calf and human lens

Abstract

By using measurements of the intensity of light scattered from intact calf lenses, we have determined a number of reagents that induce nuclear and cortical opacification at body temperature. Diffusion of buffered saline solutions of glycerol, other glycols, urea, guanidine hydrochloride or glycine into the lens reverses the opacity of all the reagent-induced cataracts. Similar findings are obtained with lens homogenates, which have gel-like properties as determined from viscosity measurements. A 50 % (by volume) glycerol or 5 M urea solution clarifies human pathologic cataractous lenses by reducing the opacification due to light scattering. These findings suggest that it may be possible, in principle, to reverse human lens cataracts chemically in situ . The scattering of laser light from quasi-periodic lattice of normal lens cells produces a regular diffraction pattern containing many Bragg spots whose positions are those predicted from the basis vectors of the cellular lattice. The intensity of the Bragg reflexions increases greatly when cataracts are formed in the calf and human lens, and falls greatly when the lenses are clarified. The spatial variation in the scattered light intensity of the Bragg spots and between these spots contains detailed information on the structure of the scattering elements associated with opacification.