Calorimetric Method for Measuring Phacoemulsification Energy Delivered During Cataract Surgery

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Physics

Background:

• Cataract surgery frequently utilizes phacoemulsification, a process involving ultrasound energy.
• Standardized measurement of ultrasound energy is crucial for comparing different surgical devices and techniques.
• Current methods lack a universal unit for energy comparison, hindering precise analysis.

Purpose of the Study:

• To quantify the ultrasound (US) energy delivered to the eye during cataract surgery in Joules (J).
• To establish a universal energy unit for comparing various US modalities and phacoemulsification systems.
• To explore the utility of Joules as a standardized metric for assessing clinical outcomes in cataract surgery.

Main Methods:

• An experimental laboratory model was developed to measure phacoemulsification energy dissipation.
• A calorimetric method was employed, using thermocouples to measure water temperature rise in response to US energy.
• Ultrasound power was tested across modalities at 10% increments from 10% to 100%.

Main Results:

• High repeatability was observed in both torsional and longitudinal US modalities (coefficient of variation < 0.5).
• Strong, non-linear correlations were found between ultrasound energy and power levels (R2 > 0.99).
• Energy measurements showed low standard deviation across tests, indicating reliable data.

Conclusions:

• A calorimetric method provides enhanced insight into total ocular ultrasound energy during cataract surgery.
• Measuring phacoemulsification energy in Joules offers a standardized comparison across platforms.
• This standardized energy measurement can serve as a clinically relevant proxy for improving surgical outcomes.