Cataract knowledge

Cataract is a common eye disease, but many people do not pay enough attention to it. There are many causes of cataracts, such as genetics, immune metabolism, poisoning, etc. Cataracts have a great impact on vision, so they need to be treated in a timely manner. Currently, most cataract treatments are surgical.

Various reasons such as aging, heredity, local nutritional disorders, immune and metabolic abnormalities, trauma, poisoning, radiation, etc. can cause lens metabolism disorders, leading to lens protein denaturation and turbidity, called cataracts. At this time, the light is blocked by the turbid lens and cannot be projected onto the retina, resulting in blurred vision. It is more common in people over 40 years old, and the incidence rate increases with age.

Overview

Cataract is a disease that occurs in the lens inside the eye. Any cloudiness of the lens can be called a cataract. However, when the cloudiness of the lens is mild, it does not obviously affect vision and is not discovered or ignored and is not classified as a cataract. According to surveys, cataracts are the most common cause of blindness and visual disability, and about 25% of humans suffer from cataracts.

Mild lens opacity that does not affect vision has no clinical significance. Only when lens opacity causes a decrease in vision can it be considered a clinically significant cataract. In epidemiological surveys, lens opacity that causes a decrease in vision by 0.7 or less is considered a diagnostic indicator.

Cataract is the leading cause of blindness and visual impairment worldwide and is more common in people over 50 years old. With the growth and aging of the population, the visual impairment caused by cataracts will increase.

Symptoms

It is bilateral, but the onset of the two eyes may be sequential. Vision progressively deteriorates, sometimes with fixed black spots visible against a bright background. Due to the changes in the refractive power of different parts of the lens, polyvision, monovision, diplopia and increased myopia may occur. Clinically, senile cataracts are divided into three types: cortical, nuclear, and subcapsular.

1. Cortical cataract is characterized by grayish-white opacity in the lens cortex, and its development process can be divided into four stages: primary stage, immature stage, mature stage, and hypermature stage.

2. Nuclear cataract: The lens opacity usually starts from the embryonic nucleus and gradually extends to the adult nucleus. It is yellow in the early stage. As the opacity worsens, the color gradually deepens to dark yellow or dark brown. The density of the nucleus increases, the refractive index increases, and patients often complain of reduced presbyopia or increased myopia. In the early stage, the peripheral cortex is still transparent. Therefore, in the dark, the pupil dilates and the vision improves, while in strong light, the pupil constricts and the vision decreases. Therefore, surgery is usually performed without waiting for the cortex to become completely opaque.

3. Posterior subcapsular cataract: Because the opacity is located in the visual axis area, it affects vision in the early stage.