an inverting sheath delivery system for medical devices , intraocular lens , and stent placement , in an eye as part of a cataract procedure or other body location or for therapeutic procedures such as the precise placement of radioisotopes to a tumor . in one embodiment , the iol replacement is positioned in the sheath and carried forward as the sheath is advanced during inversion . the iol is then deposited in the corresponding juxtaposed position proportional to the distance the sheath traveled around the tip of the pusher tube .