Sheath structure for a surgical knife

摘要

For protection of the otherwise sharp protruding end of a given instrument for use in ophthalmic or other surgery, as when the instrument is to be used only after it has traversed the major part of a scleral tunnel, a shiftable guard or shield is manipulable after it has served its function of avoiding damage to hemorrhageable tissues adjacent tunnel-wall tissue, thereby exposing the sharp end only after safely passing the hemorrhageable region. Various embodiments are described.