Inside the eyeball, there is a relatively important transparent tissue called the lens. Clinically, clouding of the lens is referred to as cataracts. Many factors, such as aging, genetics, metabolic abnormalities like diabetes, trauma, radiation, poisoning, and local nutritional disorders, can lead to damage to the capsule of the lens, increasing its permeability and losing its barrier function, or causing metabolic disturbances in the lens. This can cause the proteins in the lens to denature, leading to cloudiness of the lens, which is known as cataracts. Under a slit lamp microscope, varying degrees of cloudiness in the lens can be observed.