Determining Optimal Longitudinal Power Setting for Torsional Phacoemulsification Using Ex Vivo Bovine Lens Model

Zaugg, Brian

Determining Optimal Longitudinal Power Setting for Torsional Phacoemulsification Using Ex Vivo Bovine Lens Model

Monday, April 28, 2014: 9:09 AM

Room 152 (Boston Convention and Exhibition Center)

Brian E. Zaugg, MD, University of Utah John A Moran Eye Center, North Salt Lake, Utah, USA

Cecinio Ronquillo Jr., PhD, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA

Kevin Kirk, University of Utah, Salt Lake City, UT, USA

Brian C. Stagg, MD, Moran Eye Center, Salt Lake City, UT, USA

Jeff H. Pettey, MD, Moran Eye Center, Univeristy of Utah, Salt Lake City, UT, USA

William R. Barlow, MD, University of Utah, Salt Lake City, UT, USA

Mohammed A. Farukhi SLC, UT, USA

Isha Gupta, University of Utah School of Medicine, Salt Lake City, UT, USA

Randall J. Olson, MD, Univ. of Utah, Dept of Ophth, Salt Lake City, UT, USA

Narrative Responses:

Purpose
To determine the optimal longitudinal power setting for Ozil-IP at varying torsional amplitude settings. To test the hypothesis that increasing longitudinal power is more important at lower torsional amplitudes to achieve efficient phacoemulsification.

Methods
Porcine lens nuclei were prepared using a previously described method. Briefly, individual porcine nuclei were fixed in formalin then cut into 2.0 mm cubes. Phacoemulsification of individual lens cubes were done using Infiniti Ozil-IP at 80% and 100% torsional amplitude with 0, 10, 20, 30, 50, 75 or 100% longitudinal power. All experiments were done using a 20-gauge 0.9mm bent reverse bevel phaco tip at constant vacuum (550mmHg), constant aspiration rate (40ml/min), and constant bottle height (50cm). 25 runs were done in each experiment (25 lens cubes) primarily measuring to complete phacoemulsification of lens particle (efficiency time).

Results
Linear regression analysis shows a significant increase in efficiency with increasing longitudinal power at 80% torsional amplitude (R²=0.7 and P < 0.05) but not at 100% torsional amplitude (R²=0.3 and P = 0.2). Baseline comparison of 80% and 100% torsional amplitude without longitudinal power shows increased efficiency at 100% torsional amplitude (P < 0.0005, t-test). Comparison of 80% and 100% torsional amplitude with 100% longitudinal power shows no difference in efficiency (P = 0.13, t-test).

Conclusion
These results suggest that at lower torsional amplitudes, increasing longitudinal power is significantly important to increase phacoemulsification efficiency. Also, increasing longitudinal power does not further increase efficiency at maximal torsional amplitudes.