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. In the initial stage, there are small brownish yellow dots under the anterior capsule of the crystal, and in the later stage, there are brown rust spots under the anterior capsule, which can be detected only after the pupil is dilated in the initial stage, and in the later stage, the crystal fibers become degenerated and gradually develop into total cataract, and eventually the crystal is curled up or dislocated due to degeneration of the suspensory ligament, and the reason why cataract occurs in rust deposits is that the crystal epithelial cells become degenerated after absorbing iron, and the growth of new fibers is blocked. Even if the cataract is removed, vision cannot be restored quickly. Lens rust deposition is a clinical symptom of traumatic cataract. Direct or indirect mechanical damage to the lens can cause cloudy changes, called traumatic cataract. Patients are most often seen in children, young adult males and soldiers. How to check the lens for iron deposition? 1. History of trauma. There are signs of trauma to the eye in this disease. 2, vision loss. The patient has blurred vision, monocular diplopia or hyperopia, or a rapid decrease in visual acuity to light perception. 3. Clouding of the lens. The clouding is limited or diffuse. The clouding occurs mainly in the cortex, but also in the nucleus, which is less common in the capsule, because the capsule is thin and elastic. After injury, the cystic membrane is ruptured and rolled out or folded in. Thickening of the capsule or scarring of the epithelial proliferation, forming a “capsule clouding”. Stunned or impacted cataracts are uncommon in clinical practice and can occur alone or in combination with lens subluxation or total subluxation. The earliest change is a subcapsular clouding of the posterior capsule directly opposite the pupillary area, which in turn develops a stellate appearance or a chrysoidal clouding similar to that of a concurrent cataract. The clouding may remain stable over time or may slowly extend deeper and wider, eventually developing into a total cataract. It is worth mentioning that the cloudy changes do not necessarily appear immediately after blunt contusion, but are characterized only by the loss of the anterior and posterior subcapsular hyaline areas, which can persist for months or even years before forming typical cataract changes, known as delayed traumatic cataract. In mild cases, the subcapsular epithelial cells may remain normally active, and as new fibers are formed, the cloudy areas may be gradually squeezed deeper, showing a partially receding resting state. In most cases, traumatic iridocyclitis can be combined with post-pupillary adhesions, and in severe cases secondary glaucomatous manifestations such as iris bulging can also be seen. There is a condition associated with trauma in which an impinging force from directly in front of the pupil can imprint the iris pigment ring corresponding to the pupil on the surface of the anterior lens capsule, known as the Vossius ring. It consists of iris detached pigment granules, sometimes mixed with a few red blood cells. If it is not accompanied by parenchymal clouding of the lens, vision is usually not affected.