Heat production: Longitudinal versus torsional phacoemulsification.
OBJECTIVE
To compare the heat production of longitudinal versus torsional phacoemulsification under strict laboratory test conditions.


METHODS
Department of Ophthalmology, David Geffen School of Medicine at UCLA, and Jules Stein Eye Institute, Los Angeles, California, USA.


METHODS
Two Infiniti phacoemulsification handpieces were inserted into silicone test chambers filled with a balanced salt solution and imaged serially using a thermal camera. Incision compression was simulated by suspending 25.3 g weights from the silicone chambers. To simulate occlusion of the phacoemulsification tip, the aspiration line was clamped. Peak temperatures were measured 0, 10, 30, 60, and 120 seconds after the commencement of continuous ultrasound power. The 2 handpieces, operating exclusively in longitudinal or torsional modes, were compared 3 ways: (1) using the same power displayed on the instrument console, (2) using identical stroke lengths, and (3) using the same applied energy, a product of stroke length and frequency.


RESULTS
For all 3 comparisons, torsional phacoemulsification resulted in lower temperatures at each time point. At the same displayed power setting, the scenario most familiar to cataract surgeons, longitudinal phacoemulsification elevated temperatures up to 41.5 degrees C more than torsional phacoemulsification.


CONCLUSIONS
Torsional phacoemulsification generated less heat than longitudinal phacoemulsification in all 3 comparison tests. Lower operating temperatures indicate lower heat generation within the same volume of fluid, and this may provide additional thermal protection during cataract surgery.
Han
Young Keun
YK
Department of Ophthalmology, David Geffen School of Medicine at UCLA, and the Jules Stein Eye Institute, Los Angeles, California 90095-7002, USA.
Miller
Kevin M
KM
D006358:Hot Temperature; D008954:Models, Biological; D018918:Phacoemulsification / Q000379:methods*; D013817:Thermography; D014464:Ultrasonic Therapy / Q000295:instrumentation*