A vitrectomy probe , comprising: an outer cutting tube with an outer port side opening; an inner cutting tube , positioned inside the outer cutting tube, wherein the inner cutting tube has an open distal end having a cutting edge; wherein the inner cutting tube further comprises a distal side port with a distal side port cutting edge positioned on the distal side port such that as the inner cutting tube retracts inside the outer cutting tube, tissue entering the outer port side opening also enters the distal side port of the inner cutting tube to be cut by the distal side port cutting edge as the inner cutting tube is retracted in the outer cutting tube; a diaphragm coupled to the inner cutting tube , wherein the diaphragm is located inside a drive chamber and the diaphragm is configured to move back and forth inside the drive chamber as air is alternately supplied and vented on either side of the diaphragm in the drive chamber; wherein movement of the diaphragm causes the inner cutting tube to oscillate inside the outer cutting tube such that the open distal end of the inner cutting tube moves back and forth across the outer port side opening to cut tissue entering the outer port side opening; characterised in that the diaphragm comprises an open-stroke side with a first contact surface that contacts an inner drive chamber wall when the inner cutting tube is in a retracted position; and the diaphragm comprises a closed-stroke side with a second contact surface that contacts an opposing inner drive chamber wall when the inner cutting tube is in an extended position; and wherein the first contact surface comprises a material with a lower hardness than the second contact surface . an outer cutting tube with an outer port side opening; an inner cutting tube , positioned inside the outer cutting tube, wherein the inner cutting tube has an open distal end having a cutting edge; wherein the inner cutting tube further comprises a distal side port with a distal side port cutting edge positioned on the distal side port such that as the inner cutting tube retracts inside the outer cutting tube, tissue entering the outer port side opening also enters the distal side port of the inner cutting tube to be cut by the distal side port cutting edge as the inner cutting tube is retracted in the outer cutting tube; a diaphragm coupled to the inner cutting tube , wherein the diaphragm is located inside a drive chamber and the diaphragm is configured to move back and forth inside the drive chamber as air is alternately supplied and vented on either side of the diaphragm in the drive chamber; wherein movement of the diaphragm causes the inner cutting tube to oscillate inside the outer cutting tube such that the open distal end of the inner cutting tube moves back and forth across the outer port side opening to cut tissue entering the outer port side opening; characterised in that the diaphragm comprises an open-stroke side with a first contact surface that contacts an inner drive chamber wall when the inner cutting tube is in a retracted position; and the diaphragm comprises a closed-stroke side with a second contact surface that contacts an opposing inner drive chamber wall when the inner cutting tube is in an extended position; and wherein the first contact surface comprises a material with a lower hardness than the second contact surface . <EOS>