Anterior chamber temperature rise during torsional versus longitudinal phacoemulsification: an experimental porcine...

Previous studies have reported lower thermal profiles with torsional ultrasound than with longitudinal ultrasound; however, the mechanical determinants underlying this difference remain incompletely understood. In particular, the mechanical determinants of intraocular temperature behavior under controlled experimental conditions remain unclear. Therefore, this study aimed to compare anterior chamber temperature behavior between longitudinal and torsional ultrasound under standardized experimental conditions, including settings with nominally comparable tip-excursion parameters.

Anterior chamber temperature changes were evaluated using porcine eyes under standardized experimental conditions. Continuous longitudinal and torsional ultrasound were applied with controlled irrigation and aspiration settings. Ultrasound power settings were adjusted to create nominally comparable tip-excursion conditions between the two modalities. Temperature was continuously recorded, and temporal temperature profiles were analyzed.

Under identical machine settings, torsional ultrasound produced a significantly smaller increase in anterior chamber temperature than longitudinal ultrasound. However, when nominally comparable tip-excursion settings were used, temperature rise did not differ significantly between the two modalities. In both ultrasound modes, anterior chamber temperature increased rapidly after activation and reached a plateau within approximately 20 s.

Under controlled low-flow experimental conditions, torsional ultrasound produced a smaller increase in anterior chamber temperature than longitudinal ultrasound. However, this difference was not observed under nominally comparable machine-level tip-excursion settings. These findings suggest that tip-motion characteristics may contribute to intraocular temperature behavior during ultrasound activation.