Energy usage best with micro-burst torsional phacoemulsification, physician says

April 1, 2008

Micro-burst torsional phacoemulsification seems to be a good choice of power modulation in that it requires the least energy usage at the expense of slightly greater foot pedal time when compared with continuous torsional phaco.

Key Points

London-Micro-burst torsional phacoemulsification seems to be a good choice of power modulation, according to Richard B. Packard, MD, FRCS, FRCOphth. He is director of the clinical service unit, County of Berkshire, based at the Prince Charles Eye Unit King Edward VII Hospital Windsor, and director, Arnott Eye Associates, London. Micro-burst torsional phaco uses the least energy, although slightly greater foot pedal time, when compared with continuous torsional phacoemulsification, he added.

"Longitudinal phacoemulsification was the first technology available that was initially continuous energy and later became pulsed energy and, finally, burst, micro-pulse, and micro-burst. Although these [technologies] certainly reduced the amount of heat and energy released in the eye, there was still an issue related to repulsion and the release of free radicals from cavitation. Attempts have been made to move the tip in different directions, and the latest attempt is horizontally movement of the curved tip at ultrasonic frequencies," Dr. Packard said.

The latest technology is attractive because side-to-side oscillations using a curved tip facilitates more efficient cutting, he added. The movement of the tip does not compress the tissue but shears through it in contrast with traditional longitudinal phaco, he said. In addition, because the tip cuts to the right and left at a greater frequency, Dr. Packard speculated that the cutting might be more efficient, showing temperature charts to indicate that less dissipation of heat occurred in the eye compared with traditional longitudinal phaco.

Dr. Packard compared cumulative delivered energy and foot pedal time among the three groups, because, as he explained, it is difficult to compare traditional ultrasound measurements with the instrument used in this study with longitudinal phacoemulsification because of the differences in the settings. Twenty patients were included in each group.

"In this study, there seemed to be a difference in cumulative delivered energy between the continuous pulsed and burst energy. When using continuous horizontal movement of the tip, there is a shorter time to removal of the nuclei," he said.

A video showed that because no repulsion at the tip occurs, the nuclear fragments remain attached to the tip. "This is one feature that many surgeons find attractive about this technology. In addition, torsional phaco is very efficient for use with hard cataracts. I have not felt the need to use additional longitudinal phaco," Dr. Packard said.

"The lowest energy usage was with the micro-burst energy program, as expected. When micro-burst energy was compared with continuous torsional phacoemulsification, there was slightly greater foot pedal time. Micro-pulsing was the program that worked least well with the settings used in this study. I believe that micro-burst torsional phaco seems to be a good compromise between energy dissipation and efficiency," he concluded.