Provided herein are vitrectomy instruments and related systems and methods in which example vitrectomy instruments have multiple rotating cutting edges for severing vitreous fibers. An example vitrectomy instrument may include a handle； an outer tube； and an inner tube configured to be rotated within the outer tube in multiple oscillating rotational cycles. The outer tube may include a port disposed at a distal end thereof. The inner tube may include at least first and second forward cutting edges, so that rotation in a first rotational direction results in both the first and second forward cutting edges cutting vitreous fibers drawn into the port. The inner tube may also include one or more backward cutting edges, so that rotation in a second rotational direction results in one or more backward cutting edges cutting vitreous fibers drawn into the port. Additional forward and/or backward cutting edges may be provided.
