Comparison of Vacuum and Aspiration on Phacoemulsification Efficiency and Chatter Using a Monitored Forced Infusion System.

Abstract

PURPOSE: To evaluate the effect of vacuum and aspiration rates on phacoemulsification efficiency and chatter using a monitored forced infusion system. DESIGN: In&#xa0;vitro animal study. SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. PROCEDURES: Formalin-soaked porcine lenses were divided into 2&#xa0;mm cubes (tip diameter, 0.9&#xa0;mm). Vacuum levels were tested at 200, 300, 400, and 500&#xa0;mm Hg; aspiration rates at 20, 35, and 50&#xa0;mL/min. Torsional power was set at 60% and intraocular pressure at 50&#xa0;mm Hg. RESULTS: Increasing vacuum increased efficiency regardless of aspiration rates (R(2)&#xa0;= 0.92; P&#xa0;= .0004). Increasing aspiration further increased efficiency when vacuum was at 400 and 500&#xa0;mm Hg (P&#xa0;= .004 for 20 vs 35&#xa0;mL/min, P&#xa0;= .0008 for 35 vs 50&#xa0;mL/min). At 200 and 300&#xa0;mm Hg, efficiency only improved when increasing aspiration to 35&#xa0;mL/min (P < .0001 with 20 vs 35&#xa0;+ 50&#xa0;mL/min). Chatter improved with increasing vacuum, up to 400&#xa0;mm Hg (P&#xa0;= .003 for 200 vs 300&#xa0;mm Hg and P&#xa0;= .045 for 300 vs 500&#xa0;mm Hg). A similar trend of improved chatter was seen with increasing levels of aspiration. CONCLUSIONS: Vacuum improved efficiency up to 500&#xa0;mm Hg independent of flow. Flow has an additive effect on efficiency through 50&#xa0;mL/min, when vacuum is at 400&#xa0;mm Hg or higher, and only up to 35&#xa0;mL/min at vacuums less than 400&#xa0;mm Hg. Chatter correlated with both vacuum and flow such that increasing either parameter decreases chatter, up to 400&#xa0;mm Hg with vacuum.