Ivan A Cardenas,1,2 Reiker G Ricks,1,2 Jenna L Jensen,1,2 Tanner K Nelson,1,2 William R Barlow Jnr,1 Randall J Olson,1 Jeff H Pettey1 1Department of Ophthalmology and Visual Sciences, John a Moran Eye Center, University of Utah, Salt Lake City, UT, USA; 2University of Utah School of Medicine, Salt Lake City, UT, USACorrespondence: Jeff H Pettey, John a Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT, 84132, USA, Tel +18015812352, Fax +18015813357, Email [email protected]: To determine if using different phacoemulsification (phaco) tips will impact thermal energy output utilizing calorimetry.Methods: The Alcon Centurion was used with the Infiniti OZil handpiece and balanced, hybrid, or MST Dewey A1 mini tip. Settings were 100% power, continuous torsional or longitudinal ultrasound, 0mmHg vacuum limit, and flow rate 12mL/min. Outflow tubing was removed from the handpiece and inflow tubing was manually occluded. The handpiece tip was placed into the calorimeter filled with 50mL of degassed deionized water and ultrasound was initiated for 1 minute. Temperature rise and cumulative dissipated energy (CDE) were recorded; ten trials were performed for each group.Results: Statistically significant differences in energy output, measured in Joules, were found between all three tips in both ultrasound modes. Balanced tips showed the highest output, Dewey tips had the lowest. Hybrid tips had significantly increased output in longitudinal mode, whereas Dewey tips had significantly decreased output in longitudinal mode. No significant differences were seen in CDE between tips in either ultrasound mode, but significant increases were seen in longitudinal mode within each tip.Conclusion: This study demonstrated differences in thermal energy production of three different phaco handpiece tips. This provides insight into how thermal injuries occur and what might cause these differences. Our methodology provides a novel way for accurate energy measurement at the tip, though it differs when compared to external energy production measurements. Surgeons should take into consideration the significant variability in thermal energy created by handpiece tips.Plain Language Summary: Modern cataract surgery employs phacoemulsification, a technique that breaks apart a cataract using ultrasonic energy. A rare but possible complication of this technology is thermal (heat) injury. Several factors contribute to energy generation during cataract fragmentation, such as friction at the incision site and impedance of flow rate. This study examines the thermal energy produced at the handpiece tip, where ultrasonic movement occurs. The energy delivered to the eye from the handpiece consists of mechanical energy in the form of kinetic and acoustic energy, leading to cavitation, mechanical disruption of the lens, and heat. It remains unclear how the design of phacoemulsification tips influences the energy transfer from piezoelectric crystals to the mechanical energy delivered to the eye. We used calorimetry to measure the thermal energy output, measured in Joules, between three different tips in longitudinal (forward and backward) and torsional (side to side) ultrasound modes, using the same settings, handpiece, and machine. The handpiece tip was submerged in the calorimetry chamber with water and operated for 60 seconds; a temperature probe measured the temperature change. The temperature changes were converted to energy and compared, and the energy measurement generated by the machine was recorded. We found significant differences in energy output between the three tips in both ultrasound modes, the Dewey tip demonstrated the lowest energy output and the balanced tip had the highest, in torsional and longitudinal mode. We found the measured energy differed significantly from the machine-generated measurement. These findings highlight the variability in energy output and expand on the potential contributing factors to energy generation and thermal injury in cataract surgery.Keywords: cataract surgery, output, thermal injury, ultrasound mode, variabilit
