Abstract: A capsulorrhexis instrument that is retractable within a tube and extendable into a position projecting out of the tube. The instrument comprises a flexible band having a razor sharp cutting edge which is fixed to a plunger and located within an inserter tube. While in its retracted position within the inserter tube, the flexible band assumes an elliptical or oblong shape. However, when the flexible band is in its extended position outside of the inserter tube such as inside the eye, it expands into a circular shape whose cutting edge is sufficiently sharp to cut lens capsular tissue in response to pressure being applied to the lens capsular tissue by the cutting edge. The dimension to which the flexible band expands to reach the circular shape upon becoming clear of the inserter tube is larger than a cross-section of the gap defined by the inserter tube through which the flexible band travels in its elliptical or oblong shape.