Histochemical localization of intraocular copper foreign bodies

Alizarin blue, rhodanine, and rubeanic acid stains cytochemically localized copper in rabbit eyes harboring intravitreal copper foreign bodies of varying copper composition. Local deposition presented in small amounts in areas adjacent to the foreign body (fibrous capsule, adjacent retina, and surrounding macrophages). The localized pattern was more frequent with the 60% copper alloy, when the foreign body was encapsulated or shiny, and when the aqueous copper concentration was normal. The generalized pattern of copper deposition revealed moderate to marked amounts of copper within the following multiple intraocular structures: (1) the posterior cortex of the lens, (2) the vitreous cavity, either in free-floating macrophages or in macrophages on the surface of the retina, (3) the retina, either within monocytic macrophages, Müller cells, or extracellularly in granular clumps, and (4) the fibrous capsule around the foreign body. Copper in several eyes was observed within macrophages that were clustered around the central retinal vessels within the optic nerve. The generalized pattern was frequent with the pure copper foreign body, when the copper foreign body was tarnished, and when copper concentration of the aqueous humor was elevated. There was a direct toxic effect of copper on the lens in the form of local opacification in the posterior cortex but no clinical or histochemical evidence of a Kayser-Fleisher ring or a sunflower cataract.