Abstract
Purpose:
To compare the flow rate and duty cycle between two ultra-high-speed vitrectomy systems: pneumatic with spring return (SR) and dual pneumatic (DP) cutters.
Methods:
Flow rate was calculated using a high-sampling precision balance (2 samples/second) that measured the mass of water and vitreous removed from a vial by a vitreous cutter. The difference between the initial and final weight of water or vitreous was converted to volume removed as a function of time. Three cutters for each size (20-, 23- and 25-gauge) were tested with a SR system and a DP system using the standard duty cycle (DC) setting (biased open) at 0 (water only), 1,000, 2,000, 3,000, 4,000, and 5,000 cuts per minute with aspiration levels of 100, 200, 300, 400, 500, and 600 mm Hg. Frame-by-frame analysis of a high-speed video of the cutter was used to determine the DC.
Results:
The DC was slightly higher for the spring controlled system although without statistical significance. At lower cut rates, vitreous flow rates with the SR system tended to be higher than those obtained with the DP system. However, at higher cut rates, the DP system generated higher vitreous flow rates; in both cases the difference was not statistically significant.
Conclusions:
Spring return and dual pneumatic systems produced similar results in terms of water and porcine vitreous flow rates. Additional studies in human eyes are necessary to confirm these findings.
Keywords: 762 vitreoretinal surgery •
763 vitreous •
688 retina