Role of short-range protein interactions in lens opacifications

At high protein concentrations found in the lens, short-range order of lens proteins results in a medium of relatively constant protein density and refractive index that minimizes scattering of light. During aging and cataractogenesis of the lens, formation of high molecular weight aggregates causes fluctuations in this protein density, resulting in light scattering and a concomitant decrease in transparency, with eventual lens opacification. This review summarizes what is known about the molecular nature of short-range order, both in the normal and cataractous lens, then hypothesizes that part of this order involves heterologous crystallin interactions that may be necessary for the maintenance of lens transparency. A summary of past and possible future experimental approaches will be reviewed that can be used to ascertain the existence of these interactions and their possible changes during lens opacification.