Scanning electron microscopic findings on intraocular metallic foreign bodies

Background: The study reported here was performed to investigate morphologic intraocular reactions on the surface of metallic intraocular foreign bodies (IOFB) with scanning electron microscopy, Methods: Twenty-seven extracted IOFB were investigated. Of these, 22 were situated in the vitreous body; 19 had contact with the retina. Five IOFB had been removed from the anterior segment (control group). The duration of intraocular retention was 6 h to 24 days. Immediately after microsurgical removal the IOFB were fixed, dehydrated, dried, sputter-coated and investigated with a scanning electron microscope. Two IOFB from the vitreous were treated for collagen preservation. Results: Eighteen of 20 intravitreal IOFB showed fibers of fibrin on its surface; 11 of 20 were covered with a homogeneous layer. Within this layer a net of collagen fibers was detectable. A major cellular reaction was observed only on IOFB that injured the retina, pig ment epithelium and choroid. Conclusions: This morphologic study shows that: (1) a fibrin net develops in the vitreous around intravitreal IOFB; (2) depositions of amorphous material into the spaces of this net lead to dense coverage of the IOFB; (3) cellular reactions are not condition for the development of this coverage; (4) laceration of the retina induces a fibrocellular response.