The technique of extraction of intraocular foreign bodies

Abstract

Lose no time as infection may have time to set in or fragment may become embedded. X-ray is not needed for magnetic foreign bodies in the majority of cases. 1. (a) 70 to 80 per cent can be pulled forward from the posterior part of the eye, through the vitreous, around the lens, into the posterior chamber by a good giant magnet. 2. (b) If imbedded in the wall of the eye, this is impossible. Then localization is essential. There are three important means: (1) careful study of the path of the foreign body; (2) x-rays, which give pretty close localization but not so precise that one can be sure to cut down exactly on the foreign body; (3) for exact final localization, a short tip of a good hand magnet applied to the sclera tentatively and systematically over the suspected area. The tip is pressed lightly on the sclera and then lifted a couple of millimeters and again applied and lifted. The slight bulging of the sclera and the slight sensation of attraction reveal the exact site of the foreign body. Access to the posterior part of the eye is possible, as in operations for separated retina, by temporary section of a rectus muscle and the use of a good retractor (nonmagnetic). Cutting through the wall of the eye by the thrust of a Graefe knife may cause damaging hemorrhage. To avoid this use a diathermy knife. It is not necessary to probe the vitreous with the magnet or even to penetrate the vitreous if the foreign body has been precisely localized. Application to the lips of the wound suffices if the magnet is a good one. Avoid a giant magnet for foreign bodies that are within 2 or 3 mm. of the magnet. Avoid extensions applied to the giant magnet to act as hand magnets. After extracting diasclerally, apply a ring of diathermy micro-punctures around the site of the scleral wound to forestall separation of the retina. Results, especially late or end results, of extraction by the anterior route with the giant magnet are much better than final results with diascleral extraction by the old method, still widely used. Statistics are not available for the more modern technique here described. Details of technique for foreign bodies, magnetic and non-magnetic in different parts of the eye—cornea, anterior chamber, posterior chamber, lens, vitreous, imbedded in the wall of the eye. Importance of good light. Six causes of failure: Most important is inadequate equipment. What constitutes adequate equipment and how to test it. Hand magnet in contact should pull a fragment well over 5,000 times its weight. Giant magnet at 20 mm. should pull a fragment well over fifty times its weight. Obviously, a magnet pulling fifty will fail oftener than one pulling eighty.