A phacoemulsion tip (100), comprising: - at least one partially straight rod (108) defining a z axis (116)； - a cutting edge portion (112) at a distal end of the rod, wherein the cutting edge portion comprises at least a first and second curves (102, 104) and a point (106) of distal end, - being configured The tip to be made to vibrate ultrasonically torsionally when used with a handpiece (204) of phacoemulsion comprising an ultrasonic drive mechanism, whereby the ultrasonic torsion vibration of the tip results in at least two movements, comprising : - lateral displacement of the tip on an x axis perpendicular to the collinear z axis with a straight shank portion and perpendicular to an axis and a curve of at least a first and second curves of the tip； - torsion angle along the collinear z axis with the straight stem portion of the tip； wherein the geometry of the rod and of at least the first and second curves is configured to result, during ultrasonic torsion vibration of the tip (100), a lateral displacement of the rod (108), perpendicular to the rod (108) , of less than about 5 to 25% of the lateral displacement of the point (106) of the distal end of the tip (100) along a length of the stem extending from a proximal end of the stem to the first curve of the portion of cutting edge, where the lateral displacement of the tip (ux) is at least partially determined using the equation - it is the angle of twist of the tip, ρ is the density of a material of the tip, S (z) is the cross-sectional area of the tip along the z axis (116) collinear with the stem (108), E is Young's modulus of the tip material, Iy (z) is the moment of inertia of a cross section of the tip around the axis and perpendicu lar to the collinear axis with the rod, and l (z) is the lateral displacement along the x axis perpendicular to the collinear z axis with the rod, where at least the first and second curves (102, 104) are positioned at approximately 5 to 25% of a tip length (100) long, measure
