[Extraction of intraocular magnetic foreign body using intraocular earth magnet]

To determine the effects of extraction of intraocular magnetic foreign body with intraocular earth magnet (IOEM).

From 1992 to 1994, 22 cases with intraocular foreign body were treated with self-made intraocular earth magnet (IOEM): 2 patients with foreign body remained on lens, 7 on posterior segment of global wall, 12 lodged in the post pole of retina and 1 on the surface of optic disk. These patients were operated under microscope. The foreign bodies on the posterior segment were removed by using IOEM combined with pars plana vitrectomy.

The foreign bodies of these 22 patients were successfully removed with one operation respectively. The minimum volume of the foreign bodies was 0.5 x 0.5 x 0.5 mm3. The maximum volume of the foreign bodies was 5 x 2 x 1.5 mm3. The average maximum diameter of the foreign bodies was 2.47 +/- 1.2 mm.

Intraocular earth magnet (IOEM) is a permanent magnetic instrument with moderate magnetic power. Direct observation and detachment of the foreign body with ocular tissue are necessary during the remowal of the forreign body. This instrument is suitable for intraocular microsurgery, can be handled easily, used for extraction of foreign bodies in anterior chamber, on turbid lens and in vitreous body, in removing foreign bodies in vitreous chamber with obvious injured retina and on posterior segment, the surface of retina, and can also be applied toextract foreign bodies on optic disk as well asforeign bodies partly oldged on global wall.