Patent ID: 8496681

Claim:
A system for conducting a vitrectomy, comprising: 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 causing the pressure at the vitrector to vary according to a cycle, the varying pressure at the vitrector causing the cutting mechanism of the vitrector to open and close, wherein, at a first time in the cycle, the pulse-generating system, raises the pressure at the vitrector to a maximum pressure, and 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, and wherein the pulse-generating system includes a three-way valve and a two-way valve, the three-way valve being coupled to the gas source, the vitrector, and the two-way valve, and the two-way valve being coupled to the three-way valve and to atmosphere, and wherein, at the first time in the cycle, the three-way valve opens for a first period of time sufficient to raise the pressure at the vitrector to the maximum pressure, the maximum pressure being substantially equal to a first threshold pressure sufficient to close the cutting mechanism of the vitrector, and, at the second time in the cycle, the three-way valve closes to couple the vitrector to the two-way valve and the two-way valve opens for a second period of time sufficient to reduce the pressure at the vitrector to the minimum pressure, the minimum pressure being substantially equal to a second threshold pressure sufficient to allow the cutting mechanism to open.