Ion analyses of human cataractous lenses

The sodium, potassium, calcium, magnesium and chloride concentrations have been determined in 52 human cataractous lenses. Three main types of association between concentrations and cataract type were found. Group A, mainly nuclear cataracts, had a near normal range of concentrations. Group B, a mixture of cataract types, including mixed cataracts, had a significantly raised sodium and lowered potassium concentration, but particularly a raised calcium concentration. Group C, mainly cortical and mature cataracts, had grossly increased sodium and calcium concentrations, an increased chloride concentration and a very low potassium level. In all groups the magnesium concentration remained relatively constant.The role of calcium is particularly interesting. In pure nuclear cataracts its concentration is relatively normal and below the equilibrium concentration, but when there is cortical involvement very high calcium levels are found. The values, which are above the calculated equilibrium concentration, indicate that binding of calcium occurs. Group B and C cataractous lenses also showed a significant decrease in dry weight.