Partial or total clouding of the lens due to various causes is called cataract, and the most common type is senile cataract. The causes include environmental factors and the body’s own factors.
(1) Environmental factors: (1) Ultraviolet light: China’s plateau area is a high incidence area for cataracts. Long-term ultraviolet light exposure can lead to hardening and calcification of the lens, and can also affect the redox of the lens and make the lens degenerate and cloudy.
(2) Hypoxia and external temperature: Hypoxia and long-term operation in high temperature environment can damage the lens and cause cataract.
(3) Drugs and poisoning: such as chlorpromazine and trinitrotoluene can cause cataracts.
(4) Radiation: such as long-term exposure to X-rays, β and γ-rays, etc.
(1) Age: Cataracts are mostly seen in middle-aged and elderly people over 50 years old. With age, the lens will undergo degenerative changes and cause natural aging of the lens, leading to cataracts.
(2) Endocrine disorders: cataracts caused by diabetes, for example, are called metabolic cataracts.
(3) Malnutrition: When the body lacks certain vitamins such as vitamin E, A, B2, and certain trace elements such as calcium and phosphorus, they also tend to cause cataracts.
(4) Other diseases of the eye, such as uveitis, retinitis pigmentosa, retinal detachment, advanced glaucoma, intraocular tumor, low intraocular pressure, high myopia, etc., can lead to cataracts.
(5) Genetic or congenital factors: They are the main causes of pediatric cataract. Genetic factors are related to genes, while congenital factors are mostly due to developmental disorders in fetal period or maternal systemic diseases.
(6) Eye trauma: It can cause traumatic cataract.
To sum up, there are many causes of cataracts, including aging, trauma, poisoning, heredity, radiation, immune and metabolic abnormalities, etc.