An improved valve cutter for in-situ incision of valve leaflets which safely, efficiently, and consistently renders venous valves incompetent while minimizing frictional forces on the endothelium of the vessel and preventing inadvertent contact between cutting surfaces and the intima of the vein wall. The valve cutter includes a plurality of proximally directed prongs presenting sharp edges, where the prongs are separated by slots similarly presenting sharp edges to pierce the valve leaflets so that the cutting head is provided with a continuous cutting surface in multiple planes running along the entire forward edge of the cutting head. Fiber optics provided for viewing the valves as they are penetrated by the sharp cutting edges.