Pressure Sensor in Phaco Handpiece Tested

A phacoemulsification handpiece with a built-in pressure sensor significantly reduced the cumulative dissipated energy (CDE) and surgical time in cataract surgery compared to an identical system with the pressure sensor in the phaco machine body, said Professor Antoine Pierre Brézin. Reducing the CDE could be important for protecting the corneal endothelium and other delicate ocular tissues.

Placing the pressure sensor in the phaco handpiece rather than farther away in the machine body makes the system more responsive to tip occlusions, reducing pressure surges, Prof Brézin said. As a result, surgeons can use a higher vacuum more of the time, reducing the need for ultrasound energy to fragment the lens.

Real-life study

The Study of Active Sentry in Cataract Surgery (SASCA) involved 1,432 cases by six surgeons in five centres in France, with 800 using the built-in Active Sentry (AS, Alcon) handpiece and 632 using a non-AS machine. All surgeons used the Centurion (Alcon) phaco machine in all cases, and patient characteristics were similar for the two treatment groups.

Because SASCA was a real-life study, there were no fixed surgical parameters, leaving surgeons free to adjust them to their preferences and patient needs, Prof Brézin said. “The only comparative factor was Active Sentry or non-Active sentry.”

Mean CDE for the AS group was lower, at 8.0—ranging from 0.0 to 70.4—than in the non-AS group, at 9.3, ranging from 0.0 to 77.6 (p=0.0001). CDE was consistently lower for the AS group in each cataract grade. Both torsional and longitudinal ultrasound energy and time were lower in the AS group, with a torsional median of 661.4 versus 725.0 (p=0.0074), and longitudinal median of 49.3 versus 74.4 (p=0.0001). Ultrasound times were significantly reduced with AS. No adverse events were recorded in either group.

At 9.8 minutes, surgical duration was also shorter in the AS group than in the non-AS group, at 11.0 minutes (p=0.002), Prof Brézin reported. The more immediate fluidic response with the AS to prevent pressure surges might be the cause. “This means the surgeon was sufficiently confident to press the pedal and use high vacuum rather than high ultrasound to complete the phaco cases.”

More detailed data analysis showed longitudinal energy cut back 34% and torsional energy 9%, which Prof Brézin said provides further evidence of surgeon confidence in the ability of the handpiece-mounted sensor to better mitigate pressure surges.

“Overall, you deliver less energy to the eye, we use less ultrasound, especially less longitudinal ultrasound,” which is known to be more harmful to the corneal endothelium than torsional energy, he explained, adding shorter surgery increases patient comfort.

Although neither group presented any complications, on a larger scale, Prof Brézin anticipates the significant energy reduction linked to using the AS system will increase the overall safety of cataract surgery. The benefits of the AS-based, low-energy strategy for phacoemulsification will be further investigated.

This work was supported by an investigator-initiated study grant funded by Alcon. Prof Brézin told EuroTimes an article reporting the results of the SASCA trial has been submitted to a peer-reviewed journal.

Prof Brézin presented at the 2023 ESCRS Congress in Vienna.

Antoine Pierre Brézin MD, PhD heads the Cochin Eye Care Centre and is professor of ophthalmology at the University Paris-Descartes, both in Paris, France. antoine.brezin@aphp.fr