The pathogensis of the disease, which is not totally known now, is generally believed to be related to ultraviolet ray and holopathy such as diabetes, hypertension, arteriosclerosis, genetic factor, lens nutrition and metabolic condition. From the clinical manifestations, the disease should pertain to "Yuanyi Neizhang " (cataract) in traditional Chinese medicine. Usually, it occurs as the result of aging, debility, deficiency of liver and kidney yin and asthenia of essence and blood, or ocular malnutrition caused by digestive disorder due to spleen asthenia. In addition, when the eye is affected by the stagnated heat of liver meridian or by yin deficiency with damp-heat, the disease may also arise.