Sara Wester, M.D.
Contributing Editor
Each phacoemulsification system has unique features that strive to reduce phaco energy and heat, increase surgeon customization, and improve efficiency, all of which lead to improved visual outcomes. While many different technologies are available, this section will focus on three frequently used phacoemulsification systems and their newer variations, the Bausch & Lomb Millennium and Stellaris Microsurgical Systems, the Alcon Infiniti and AdvanTec Legacy with Neosonix, and Advanced Medical Optics’ Sovereign WhiteStar.
The Millennium Microsurgical System, developed by Bausch & Lomb, has the choice of the Advanced Flow System (AFS) peristaltic pump or the Venturi pump. The direct-response Venturi vacuum system provides simultaneous, Dual-Linear foot pedal control of flow, aspiration and ultrasound power. The Optional Advanced Flow System delivers advanced flow-based technology for greater intraoperative stability, efficiency and control (with Dual-Linear™ foot pedal) that is customizable by the surgeon. These customizable fluidics allow for enhanced surge protection even at high flow rates thus enabling the surgeon to maintain high vacuum levels with a stable chamber throughout the case. In addition, the close control of fluidics increases precision and efficient performance. The Millennium fluidics system was the first aspiration pump system to allow for flow or vacuum-based aspiration and simultaneous control of either flow or vacuum and ultrasound power. This complete separation of fluidics from ultrasonics reduces phaco energy and heat because the surgeon can increase and modify fluidics without increasing power, thus allowing for lower power phacoemulsification. The Millennium phacoemulsification system offers a lower-frequency phaco tip with hyperpulse power that allows for “cooler” phaco energy. These technologies strive to lower phaco energy release and improve visual outcomes.
The Stellaris Vision Enhancement system is a new Bausch and Lomb phacoemulsification system released in 2008. It offers similar fluidics to the Millenium in that it allow the surgeon to use flow mode exclusively or select intraoperatively between flow- or vacuum-response, depending on the stage of the surgery. It has a sensing technology which closely monitors vacuum levels in flow and vacuum mode and closely regulates vacuum in vacuum mode allowing for minimum post-occlusion surge, a rapid return to steady state and enhanced followability and aspiration control. The phacoemulsification handpiece has a six-crystal design for improved cutting and cavitation which will allow more advanced microincision surgical techniques, permitting smaller incisions.
The Alcon INFINITI® Vision System has an advanced fluidics system with a low-compliance design that uses a thick-walled polymer aspiration tubing and molded fluid paths. These advances decrease post-occlusion surge and increase fluidic accuracy and response and also allow for increased vacuum levels. The pump mechanism in this system is a peristaltic pump with tapered rollers, providing instantaneous response without fluctuation. Two delivery systems, the OZil® Torsional Handpiece and the AquaLase® Liquefaction Device allow for customization of phacoemulsification to each surgery. The OZil® Torsional system is composed of a handpiece that delivers side-to-side oscillating ultrasonic movement, which shears the lens material and thus decreases repulsion and increases followability and cutting efficiency. In addition, this system has the potential to reduce fluid usage because of decreased repulsion. The AquaLase® Liquefaction Device uses pulses of BSS® to perform phacolysis and delaminate and separate lens tissue. The surgeon can modify the system by changing volume and velocity (which affect pulse strength); varying pulse rate, and activating burst. This Aqualase system is not widely used, in part because it is limited to lenses with only mild nuclear sclerosis.
Alcon has also more recently developed the AdvanTec Legacy with NeoSonix which is an upgrade to the Legacy system that combines ultrasonic with sonic oscillatory motion for lower energy phacoemulsification. The sonic oscillation tends to prevent occlusion, reducing the risk of surge and damage to the posterior capsule. In addition, the tip repositions the nuclear material automatically for better engagement, reducing the amount of reposition of material required by the surgeon. Fluidics on this system can be closely controlled and the surgeon can choose between linear flow or vacuum in foot position 2, thus reducing the amount of energy delivered.
Advanced Medical Optics’ Sovereign WhiteStar is an upgrade for the Sovereign phacoemulsification system that offers high-rate microbursts of phaco energy. The pulses of ultrasound energy are faster than the thermal relaxation time of the tissue, so that there is less heat buildup at the tip. This system works similarly to a fluorescent lightbulb which alternates rapidly between on and off and thus remains cool and provides more efficient illumination. In addition, because less energy is released, there is decreased repulsion and turbulence. The micropulse technology also creates fast bursts of energy with “transient” cavitational energy, which enables more bubbles to implode in very small volumes, thus increasing efficiency. The Fusion™ Fluidics system used in the AMO phacoemulsification systems anticipates intraocular changes and proactively adjusts by adapting to changes in vacuum immediately and automatically based on pre-set specifications. These protective mechanisms allow for higher vacuum and flow, which reduce phaco time and increase efficiency.
Each company has developed phacoemulsification systems with unique technological advancements in an effort to increase surgeon control, reduce phaco power and heat generation, increase efficiency and improve visual outcomes. The decision of which machine to use is dependant on surgeon preference, familiarity and surgical cases.
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