1, ultraviolet radiation: the cloudiness of the lens is related to long-term exposure to ultraviolet light, especially long-wave ultraviolet light. 295nm or more wavelengths of ultraviolet light can easily penetrate the cornea and be effectively absorbed by the crystal, epidemiological studies suggest that long-term exposure to sunlight can significantly increase the risk of cataract in humans. 2. Diabetes: The incidence of cataract in diabetic population is significantly higher than normal population. With the increase of blood sugar level, the incidence of cataract also has a tendency to increase, and the age of cataract in diabetic patients is significantly earlier, so diabetic patients should have regular eye examination. 3, peroxidation reaction: experiments have confirmed that cataracts can be caused when the enzyme system, protein and biological resistance to oxidative attack in the lens are insufficient. Vitamins in food such as carotene, vitamin B2, vitamin C, vitamin E and other substances can enhance the antioxidant effect, so we should eat more fruits and vegetables in our daily diet. 4, drugs: If long-term systemic or local application of high-dose glucocorticoids can induce cataracts; patients using sedatives have an increased chance of cataracts, such as tranquilizers and drugs such as phenothiazine for the treatment of schizophrenia. 5, other: epidemiological investigation found that the occurrence of cataracts is related to smoking and drinking history, blood pressure and even gender.