INFLUENCE OF CALCIUM ON LENS FIBERS

The influence of different concentrations of Ca on isolated lens fiber bundles was studied in vitro. Lens fibers were obtained from subcapsular and 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 microscope and EM. The subcapsular lens fibers rapidly swelled and broke down in the presence of Ca concentrations equivalent to those present in aqueous humor. The deeper cortical fibers were much more resistant and lens fibers were hardly affected in incubating media containing no Ca. Fiber swelling in the presence of Ca 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 Ca was present. However, the speed of the process accelerated with increasing Ca concentration in the incubating media. Ca probably plays an important role in the formation of subcapsular cataracts. By increasing lens fiber permeability to Na and water, Ca induces lens fiber swelling.