A 35-year-old man sustains a penetrating ocular injury with a metallic intraocular foreign body (IOFB) from grinding. He is referred 2 weeks later. Slit-lamp shows golden-brown rust deposits in the anterior lens capsule and iris (Vossius ring), and visual field constriction. This pattern of injury is called:
- A Siderosis bulbi from retained iron foreign body causing electroretinographic changes and visual field constriction ✓
- B Chalcosis (copper toxicity) causing sunflower cataract and ring deposits
- C Sympathetic ophthalmia from penetrating injury
- D Endophthalmitis from retained vegetable foreign body
Explanation
Siderosis bulbi results from the slow oxidative dissolution of a retained iron-containing intraocular foreign body, releasing ferrous ions that are deposited within the epithelial cells of the iris, lens, ciliary body, retina, and trabecular meshwork. Clinical findings include a rust-brown discolouration of the iris, anterior capsular and subcapsular iron deposits (in a mossy pattern), heterochromia, glaucoma, and electroretinographic changes (reduced b-wave on ERG) from retinal receptor toxicity leading to progressive visual field constriction and nyctalopia. Urgent removal of the IOFB is required to prevent irreversible damage. Chalcosis from copper produces a sunflower cataract and Kayser-Fleischer-like ring.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.