The influence of calcium on lens fibers

Abstract

The influence of different concentrations of calcium on isolated lens fiber bundles was studied in vitro. Lens fibers were obtained from subcapsular as well as deeper cortical regions of rat and rabbit lenses. The morphological changes which occurred during incubation were studied in the phase contrast microscope and, after fixation, in the light and electron microscope. The subcapsular lens fibers rapidly swelled and broke down in the presence of calcium concentrations equivalent to those present in aqueous humour. The deeper cortical fibers were much more resistant and lens fibers were hardly affected in incubating media containing no calcium. Fiber swelling in the presence of calcium had a segmental appearance and was located at the ends of the lens fibers. Here, membrane enclosed spheres were formed and shed. Large aggregates developed as a result of lens fiber fusion. The pattern of lens fiber swelling and breakdown was similar whether or not calcium was present. However, the speed of the process accelerated with increasing calcium concentration in the incubating media. Calcium probably plays an important role in the formation of subcapsular cataracts. By increasing lens fiber permeability to sodium and water, calcium induces lens fiber swelling.