The most common cause of blindness is cataract. The possible causes, radiation, sugar, drugs, trauma, nutrition, congenital, secondary to eye disease etc. Generally, the opacification of the lens are the result fa oxidation of the lens fibers. The basis for lens transparency is the structural integrity of lens fibers. Opacities were occur if there is a significant amount of high molecular weight protein aggregates. If Ca ions combined with lens ${alpha}$-crystallin proteins, the lens fibers were aggregated by high molecular weight proteins and the lens were opacified. If Ca ions detached from lens ${alpha}$-crystallin proteins, the lens fibers were aggregated by low molecular weight proteins and the lens were re-cleared. We need to find out the variety of factors can initiated the process of age-related cataract. And to understanding the mechanism how the various kind, of diabetic cataracts occur.