2020–2021 BCSC Basic and Clinical Science Course™
11 Lens and Cataract
Chapter 8: Phacoemulsification for Cataract Extraction
Key Concepts and Advances in Phaco Power Delivery
Torsional and Elliptical Phacoemulsification
Other advances in phacoemulsification technology can also reduce chatter and the total amount of phaco energy used. For example, in torsional phacoemulsification, the piezoelectric crystals of the phaco handpiece produce an oscillatory (torsional) movement, which is amplified by use of a bent phaco tip (eg, a Kelman-style phaco tip).
Figure 8-3 Pulse-versus burst-mode phacoemulsification. A, In pulse mode, foot pedal excursion provides linear control of ultrasound power, with a fixed duty cycle (50% in this case) and number of pulses per second. B, In burst mode, foot pedal excursion provides linear control of number of bursts per second, with a fixed ultrasound power (25% in this case) and burst duration.
(Data modified from Seibel BS. Phacodynamics: Mastering the Tools and Techniques of Phacoemulsification Surgery; 4th ed. Slack; 2005:121, Fig 1-55.)
The greater side-to-side movement at the tip may allow for greater shearing forces to assist in nucleus disassembly. Another system utilizes a combination of transverse and longitudinal modalities; the resulting elliptical cutting pattern may enhance nucleus emulsification.
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.