Effect of cutting phases on flow rate in 20-, 23-, and 25-gauge vitreous cutters

Abstract

Background: Vitrectomy systems are now available with 20-, 23-, and 25-gauge vitreous cutters and are designed to be used with conventional or new generation pneumatic actuation technology.

Methods: Five vitreous cutters using pneumatic actuation technology were studied. Flow rates were evaluated using porcine vitreous. A high-speed camera timed the cutting phases (open, closing, closed, and opening), and duty cycle was calculated. The cutting port surface area and internal shaft surface areas were calculated.

Results: Increasing cut rate decreased the average open phase duration without affecting other cutting phases. The opening and closing phases of vitreous cutters using new generation pneumatic actuation technology were longer than those for other vitreous cutters. Flow rate was correlated to internal shaft surface area.

Conclusion: In addition to confirming the importance of duty cycle at high cut rates, this study demonstrated that the transition phases should also be considered when one is evaluating the efficiency of a vitreous cutter.