Abstract: A surgical instrument that creates a circular cut 42 of almost any diameter in the lens capsule 50 of the eye, yet its entire diameter is less than 1 mm when inserted into the eye. A cutting edge 14 is affixed to the distal tip of a super-elastic rod 11 with its distal end formed into a circular loop. The circular loop is first retracted inside of an outer tube member 12, and then the tube 12 is inserted into the eye. The loop is then expelled from the tube 12, allowing the loop to reform inside of the eye. As the loop is retracted back into the tube 12, the cutting edge 14 follows the circular path of the loop, cutting a circular opening (a capsulorrhexis) 42, into the lens capsule 50.