Iron is the most common intraocular foreign body, the foreign body in the lens can form a limited cataract, if the iron foreign body is small, it can exist in the crystal for many years without obvious reaction, iron can oxidize in the eye and gradually spread in the eye, forming ocular rust deposits, including rust deposits in the cornea, iris, lens, and retina, eventually leading to blindness, the rust deposits in the eye are related to the size and location of the intraocular foreign body. Larger and posterior foreign bodies tend to migrate to the posterior segment of the eye. Lens rust deposition is a clinical symptom of traumatic cataract. Direct or indirect mechanical injury to the lens can produce cloudy changes, called traumatic cataract. Patients are most often seen in children, young adult males, and warriors. Differential diagnosis of iron deposition in the lens: 1. Radiation cataract (1) Patients have a history of radiation exposure. (2) Chronic X-rays and other radiation damage to the lens, clouding mostly starts from the posterior pole, initially there can be 3 manifestations of posterior subcapsular cortical vesicles, posterior subcapsular foggy clouding and posterior subcapsular cortical punctate clouding, which can occur separately but are mostly mixed. (3) Vacuoles appear in the subcortical layer of the posterior capsule. The vacuoles are small and round, or remain unchanged for a long time, or change into small white dots by cheese shape, which cannot be absorbed by themselves and gradually expand to the anterior and equatorial parts. (4) After a long time, the clouding of posterior subcapsular cortex is more foggy and mixed with dotted flakes, and the whole is in the shape of thin round flakes, which are initially confined to the 2mm radius near the posterior pole, near the posterior capsule and far from the posterior part of the nucleus. 2. Highly myopic subcapsular cortical clouding is often brownish, and the cortex is completely clouded from the posterior nucleus. 3, diabetes-induced lens lesions Although they can be located in the posterior subcapsular cortex, the small vacuoles are large, not round, numerous, integrated into clusters, fused with each other, and can increase or decrease in size. The small vesicles caused by radiation are mainly located in the posterior pole under the posterior capsule and do not reach the positive posterior pole. It is characterized by small and rounded, stable vesicle morphology that remains unchanged for a long time. These vesicles are associated with diabetes. 4, body copper deposition If the copper content is more than 85%, there is very obvious damage to the eye tissue. Pure copper can cause septic changes in the eye. Cataracts caused by copper foreign bodies in the lens can cause iridocyclitis in the anterior chamber and damage to the optic nerve, retina and choroid in the posterior pole. Copper ion deposition in various tissues of the eye is known as patina, and deposition in the posterior elastic layer of the cornea may have a blue-green ring (Kayser-Fleisher ring). The iris turns light green, there are multi-colored vesicles in the vitreous, and the retina has green pigment. The crystal develops sunflower-like cataract due to copper deposition, with iridescent changes in the pupil area and a velvety crystal surface. The posterior capsule of the lens is like green shark grass. Sunflower-like cataracts do not affect vision very severely. If a copper foreign body is found in the lens, it must be removed as soon as possible. This is because even if there is tissue to encapsulate the foreign body, it can cause necrosis of the eye tissue and cause blindness. This is different from an intraocular iron foreign body.