Calcium distribution in the human eye lens

The distribution of calcium in the human eye lens was investigated using the oxalate-pyroantimonate technique. In epithelial cells and superficial cortical fibers calcium is sequestered and tightly bound to proteins in the endoplasmic reticulum, nuclear envelope, Golgi cisterns and mitochondria. In intermediate fibers these cell organelles are broken down and the liberated calcium is ionically bound to the phospholipids at the extracellular side of the fiber-limiting membrane. It is argued that calcium is probably additionally bound to beta-crystallin. This site-specific variation in calcium storage might explain the deeper cortical localization of early focal dot opacities and retrodots.