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

Purpose: To evaluate the effect of vacuum and aspiration rates on phacoemulsification efficiency and chatter using a monitored forced infusion system.

Design: In 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 mm cubes (tip diameter, 0.9 mm). Vacuum levels were tested at 200, 300, 400, and 500 mm Hg; aspiration rates at 20, 35, and 50 mL/min. Torsional power was set at 60% and intraocular pressure at 50 mm Hg.

Results: Increasing vacuum increased efficiency regardless of aspiration rates (R(2) = 0.92; P = .0004). Increasing aspiration further increased efficiency when vacuum was at 400 and 500 mm Hg (P = .004 for 20 vs 35 mL/min, P = .0008 for 35 vs 50 mL/min). At 200 and 300 mm Hg, efficiency only improved when increasing aspiration to 35 mL/min (P < .0001 with 20 vs 35 + 50 mL/min). Chatter improved with increasing vacuum, up to 400 mm Hg (P = .003 for 200 vs 300 mm Hg and P = .045 for 300 vs 500 mm Hg). A similar trend of improved chatter was seen with increasing levels of aspiration.

Conclusions: Vacuum improved efficiency up to 500 mm Hg independent of flow. Flow has an additive effect on efficiency through 50 mL/min, when vacuum is at 400 mm Hg or higher, and only up to 35 mL/min at vacuums less than 400 mm Hg. Chatter correlated with both vacuum and flow such that increasing either parameter decreases chatter, up to 400 mm Hg with vacuum.