Thermal Comparison of Infiniti OZil and Signature Ellips Phacoemulsification Systems

Purpose

To determine thermal characteristics of Signature Ellips (Abbott Medical Optics) and Infiniti OZil (Alcon, Inc.) transverse ultrasound and compare both with longitudinal ultrasound in clinically relevant scenarios.

Design

Laboratory investigation.

Methods

Temperature increase over baseline after 60 seconds was measured in water at positions in 90-degree increments around the sleeve near the proximal needle shaft in an artificial chamber for Ellips and OZil on continuous ultrasound with aspiration blocked and unblocked. This was also done with Signature using longitudinal ultrasound, with and without micropulse (6 ms on, 12 ms off), with aspiration blocked and unblocked, and at the OZil sleeve tip on continuous transverse mode with aspiration unblocked.

Results

OZil (8.1 ± 0.3 C) had greater temperature increase than Ellips (5.2 ± 0.3 C; P < .0001) with aspiration unblocked and blocked (29.3 ± 1.0 C vs 12.2 ± 0.7 C; P < .0001). OZil had uneven distribution of heat around the shaft (30.1 ± 0.5 C vs 28.5 ± 0.6 C; P < .0001), whereas Ellips did not (P = .57). OZil was cooler at the tip (6.6 ± 0.2 C; P < .0001). Friction in a cadaver eye incision only increased these numbers by 10% (OZil, irrigation blocked).

Conclusions

Metal stress probably creates heat at the proximal needle junction for both transverse methods. Heat generation differences between OZil and Ellips result from the manner in which they create needle motion. Incision burns may occur, especially for OZil, under nonpulsed settings during fragment removal with occlusion when reaching across the anterior chamber such that the proximal needle shaft came near the wound.