A system for conducting a vitrectomy includes: a gas source; a vitrector including a cutting mechanism that opens and closes according to a pressure at the vitrector; and a pulse-generating system receiving gas from the gas source and generating pulses at the vitrector. The pulses cause the pressure at the vitrector to vary according to a cycle, and the varying pressure at the vitrector causes the cutting mechanism of the vitrector to open and close. At a first time in the cycle, the pulse-generating system, raises the pressure at the vitrector to a maximum pressure. At a second time in the cycle, the pulse-generating system reduces the pressure at the vitrector to a minimum pressure that is greater than ambient, the pressure at the vitrector being maintained at least at the minimum pressure. The difference between the maximum pressure and minimum pressure is minimized to reduce gas consumption.