An instrument capable of providing large-area shielding within an isolated operating region, such as the eye, while being passable through a small incision in the region through which the instrument must be inserted. For example, an instrument capable of being passed through a typical 3 mm (or smaller) phacoemulsification incision without undue damage to ocular tissue, and which expands to provide large-area shielding, e.g. to occlude a large-diameter (e.g. approx. 6 mm) posterior capsule opening. The surgical instrument includes two or more leaves, the leaves being interconnected by at least one fastener in a manner that causes expansion of a leading or distal portion of the instrument when the following or proximal portions of each leaf are manipulated, whether by a user or through interaction with a wall of the incision.
