The causes of cataracts are multifaceted, except for traumatic cataracts, radioactive cataracts, congenital cataracts and diabetic cataracts which have more obvious etiologies, the cataract formation process may have multiple factors and the situation is quite complex. The pathogenesis of common senile cataracts has not been fully revealed so far, and may be related to ageing, long-term excessive exposure to ultraviolet light, genetic factors and malnutrition. In China, it has been confirmed by investigation that the incidence of cataracts is relatively higher in highland areas and areas with more sunlight radiation. This is because long-term exposure to ultraviolet radiation can affect the oxidation-reduction process of the lens, causing degeneration and clouding of the lens proteins to form cataracts. In addition, common clinical conditions such as diabetes, galactosemia and hypothyroidism can also cause cataracts.