眼内異物摘出用永久磁石

Design of a magnet for removal of intraocular foreign body

　永久磁石を使用した，硝子体手術用の磁性眼内異物摘出器具を作成した．その特徴は，同種の電磁石式の器具と比べても遜色ない程強力な磁力を持つ磁石を使用している．これは最近本邦で開発された永久磁石で，今のところ入手可能な世界で最も強力なものとされている．把持部は太さ15mm，長さ50mm，眼内挿入部は，太さ1.6mm，長さ26mmで，アルミの外套を有しクロームメッキが施されている．磁力は，1個5.5gの鉄球（パチンコ玉）5〜6個を持上げる（27.5〜33g）．オートクレープ可．硝子体切除後毛様体扁平部に幅2.4mmの切開創をつくり，磁性眼内異物を吸着して摘出する．

A new hand-held magnet was designed for the removal of intraocular ferrous material. The holder for the apparatus measures 1.5 cm in diameter and 5 cm in length. The permanent magnet, which is contained in the holder, is an alloy of neodium, ion and boron. It is one of the most powerful one of its kind and is roughly comparable, in performance, with electro-magnet of the same size. It can lift maximum of 6 steel balls weighing 5.5 g each. The tip measures 1.5 mm in diameter and 26 mm in length and is chrome-plated. The whole system weighs 40 g and is autoclavable. During actual use, the tip can be inserted into the vitreous through a 2.4 mm incision in the pars plana.