Study provides objective proof of improved efficiency of torsional phaco

March 18, 2006

Torsional phaco performed with the new OZil handpiece (Alcon Laboratories) results in more efficient surgery than conventional longitudinal phaco, said David Allen, MD, Sunderland Eye Infirmary, England.

Torsional phaco performed with the new OZil handpiece (Alcon Laboratories) results in more efficient surgery than conventional longitudinal phaco, said David Allen, MD, Sunderland Eye Infirmary, England.

Torsional phaco is a new cataract removal energy modality available for the Infiniti Vision System (Alcon). In torsional phaco, the phaco needle vibrates at ultrasonic frequency in a torsional way rather than longitudinally. The result is elimination of repulsion of nuclear material from the phaco tip and better followability.

To determine in an objective way that those features translate into improved efficiency, Dr. Allen performed a single surgeon, randomized study using the flow of balanced salt solution (BSS) through the eye during nucleus removal as a proxy measure. After calculating the sample size needed to demonstrate a statistically significant difference between groups, 84 cases were randomly assigned to surgery with the longitudinal or torsional technique, and the weight of BSS used from the start to the end of nucleus removal was determined using a precision balance.

The mean amount of BSS used was 55 gm in the longitudinal phaco group, and that was significantly greater than the 42 gm required for torsional phaco.

"Those who have had the pleasure of using torsional phaco can appreciate its improved efficiency when looking through the operating microscope," Dr. Allen said. "In this small study, we have been able to show that benefit in terms of a highly statistically significant reduction in the amount of BSS going through the eye.

"The elimination of repulsion and markedly improved followability with torsional phaco is also associated with less need for instrument manipulation in the anterior chamber, and therefore this new modality should have less potential for causing endothelial damage," Dr. Allen said. "Demonstrating that torsional phaco translates into a clinically significant difference will be a focus of my future research."