Intraocular iron-containing foreign bodies can cause siderosis bulbi, a condition in which iron molecules are deposited in the trabecular meshwork, lens epithelium, iris, and retina (Fig 5-17A). The epithelium and cortical fibers of the affected lens at first show a yellowish tinge, followed by a rusty brown discoloration (Fig 5-17B). Lens involvement occurs more rapidly if the retained foreign body is embedded close to the lens. Later manifestations of siderosis bulbi are complete cortical cataract formation and retinal dysfunction. See also BCSC Section 12, Retina and Vitreous.
Figure 5-17 Siderosis bulbi. A, Heterochromia iridis caused by siderosis bulbi. B, Discoloration of the lens capsule and cortex.
Chalcosis occurs when an intraocular foreign body deposits copper in Descemet membrane, anterior lens capsule, or other intraocular basement membranes. The resulting “sunflower” cataract is a petal-shaped deposition of yellow or brown pigment in the lens capsule that radiates from the anterior axial pole of the lens to the equator. Usually, this cataract causes no significant loss of vision. However, intraocular foreign bodies containing almost pure copper (more than 90%) can cause a severe inflammatory reaction and intraocular necrosis.
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.