Increased cutting efficiency in phacoemulsification with Sovereign WhiteStar ICE technology

Abstract

In small-incision cataract surgery, developments in machinery and software enable surgeons to use very low levels of ultrasound power to limit endothelial cell damage during phacoemulsification. Ultrasound energy is used to generate transient cavitation, the process in which gas bubbles are pulled out of the solution by excursion of the phaco probe and then violently implode, releasing energy and causing subsequent destruction of nuclear material. 1,2 The Sovereign WhiteStar phacoemulsification system (Advanced Medical Optics, Inc.) delivers ultrasound in a series of micropulses, each lasting tens of microseconds, rather than as a continuous stream of energy, and this has been shown to increase the efficiency of the ultrasound. 3,4 The greater efficiency is partly because transient cavitation tends to occur early in each segment of activated ultrasound; ie, many short pulses are more efficient than one long one. 5,6 In WhiteStar ICE technology, there is an additional burst of ultrasound at the start of each micropulse. This corresponds to an additional excursion of the phaco tip at the beginning of the micropulse, and thus creates a space between the phaco tip and the nuclear material ahead of it into which more gas-rich fluid can flow. During the remainder of the micropulse, when the normal excursion of the phaco probe is resumed, a greater degree of cavitation can occur within this extra volume of fluid. We looked at whether the WhiteStar ICE modified ultrasound delivery system allows the surgeon to increase cutting power without increasing energy output. PATIENTS AND METHODSThe study included consecutive eyes having routine phacoemulsification at a single-center randomized study at a university hospital. Each eye had cataract surgery with the Sovereign WhiteStar system alone or with the modified ultrasound delivery component of ICE. Eyes were randomly allocated to each group just before surgery using random number tables, with odd numbers assigned to the ICE group and even numbers to the without ICE group. The power settings using the Variable WhiteStar (VWS) system were the same in both groups: sculptingdmaximum power 60%, power ratio DB (ultrasound activation cycle: 8 ms on and 4 ms off, ie, 67% on); segment removald maximum power 50% (occluded) (unoccluded 20%), power ratio CD (6 ms on and 8 ms off, ie, 43% on) occluded (VWS unoccluded). The grade of cataract on dilated examination just before surgery was noted. The stop-and-chop method was used in each eye. At the end of each procedure, the equivalent phaco time (EPT) was recorded. This is calculated by the machine's software by continuously monitoring the power level activated over the course of the operation and then calculating the time for which the equivalent of 100% power would be activated. This value is essentially the area under the curve in the power versus time graph. The total ultrasound time (foot pedal activation time) and the mean phaco power were also recorded. These values were compared between the 2 groups. RESULTSFifty-eight eyes were en...

Correlation between Cataract Grading by Scheimpflug Imaging and Phaco Time in Phacoemulsification using Peristaltic and Venturi Pumps

“…It is known that the ultrasound (US) energy used during phacoemulsification is crucial. Lower levels of US power can reduce endothelial cell damage and phaco surgery planning with lowest levels of US power based on cataract density could be a challenge (3, 4).…”

“…It is known that the ultrasound (US) energy used during phacoemulsification is crucial. Lower levels of US power can reduce endothelial cell damage and phaco surgery planning with lowest levels of US power based on cataract density could be a challenge (3,4). In 2007, a new method to evaluate the nuclear component of a cataract was presented in order to enable cataract surgeons to change phaco settings preoperatively Correlation between cataract grading and phaco time based on objective and reproducible cataract density results (D.R.…”

Preoperative cataract grading by Scheimpflug imaging and effect on operative fluidics and phacoemulsification energy

“…Lower levels of US power can limit endothelial cell damage; therefore, it makes sense to plan phaco surgery with the lowest levels of US power needed based on cataract density. 2,3 In clinical settings, it is common for surgeons to alter phaco settings intraoperatively according to the density of the cataract. It would be more efficient to set phaco variables preoperatively based on objective and reproducible cataract density results.…”