Dr. Barry Seibel is a cataract surgeon and sole author and illustrator of the critically acclaimed cataract surgery textbook, Phacodynamics. He is an expert in applying engineering principles to facilitate customized surgery for each patient. Dr. Seibel is a proponent of vacuum control. “To me, it clinically makes a lot more sense than flow-based control.” He noted that Bausch + Lomb has overcome early misconceptions about vacuum control with several major advances incorporated into the Stellaris Elite® system, which Dr. Seibel considers “a phacodynamically optimized (phaco/cataract) platform.”
While some surgeons may misperceive vacuum-based systems as being inherently faster and more dangerous, in reality vacuum-based phaco machines provide more intuitive control and maintains consistent chamber stability. With Stellaris Elite, there is one fluidic control – commanded vacuum – and the machine responds based on what the surgeon asks it to do. Due to a gap in education and knowledge when early vacuum-based machines came onto the market, some surgeons were using unintended very high flow rates as a consequence of high commanded vacuum in the absence of modern safety measures discussed below. Surgeons can now adapt to and leverage the new technology by learning about the reduced flow capabilities with enhanced chamber stability for optimized vacuum-based machinery.
Dual Linear Foot Pedal
Stellaris Elite has a dual linear foot pedal that gives the surgeon “exquisite control of linear vacuum” by allowing the surgeon to modulate the vacuum level throughout the procedure to reduce post-occlusion surge. The vacuum can be increased only when the surgeon needs it. This advanced pedal gives the surgeon more finesse of control because vacuum and ultrasound are independently controlled, and the ranges of pedal travel are doubled compared to a standard pedal, thereby enhancing control sensitivity.
The dual linear foot pedal is ergonomically advanced and allows the surgeon to offset the pedal to the left or right for an even larger distance of pedal travel, which further increases control sensitivity in yaw movement.
Additionally, with the dual linear foot pedal, the surgeon can easily adjust the vacuum level depending on whether they are in the chop stage of surgery or the fragment removal portion of the procedure, without using an extra setting on the phaco machine which would be required when using a standard pedal.
Adaptive Fluidics™ System Prevents Significant Post-occlusion Surges
With Stellaris Elite, post-occlusion surges are extremely rare and surgeons don’t need to focus on this issue.1 A potential issue with older pumps is the risk of post-occlusion surge with higher vacuum levels. Stellaris Elite has a pressurized irrigation bottle, which helps to stabilize the anterior chamber. The Adaptive Fluidics proactively increases pressurization as the surgeon increases commanded vacuum, thereby maintaining chamber stability as aspiration outflow increases.1
Proactively increases infusion pressure as more vacuum is commanded in order to maintain chamber stability as aspiration outflow increases.
Fluidic Resistors Limit Flow Rate to a Safe Level
Stellaris Elite contains two fluidic resistors – one at the needle and one in the stable chamber cassette pack. The fluidic resistor controls the flow rate when higher vacuum levels are being commanded. Years ago, 19-gauge needles were used with phaco. Currently, 20- and 21-gauge needles can be used; with the smaller needle there is a greater resistance to outflow. The benefit is that slower outflow during the procedure improves chamber stability.2 In comparison, older, wider needles were associated with higher outflow rates, especially with older vacuum-based machines without pressurized infusion and dual linear pedal control.
The combination of the narrow gauge microincisional cutting needle (MICS) and stable chamber cassette provides an upper limit of outflow of 50-60 cc per minute, which is similar to the outflow limit of a flow-based machine, thus supporting the safety profile of Stellaris Elite.
With the vacuum-pump machine, the flow is readily controlled using linear commanded vacuum when the aspiration port is not occluded.1 This same vacuum control varies grip of a nucleus that is occluding the aspiration port. Conversely, with a flow pump, the surgeon presets the vacuum limit level and a commanded flow rate, although actual vacuum and flow are dependent on several variables. With a flow pump, at higher resistance (e.g. with ambient viscoelastic), the vacuum builds up, which halts the flow and reduces followability. To Dr. Seibel, “flow-based systems use a more awkward control algorithm and provide less intuitive direct control.” The followability with vacuum-based phaco machines can attract and hold onto fragments of cataract in a consistent manner, titrated by the surgeon using dual linear pedal control based on visual feedback through the microscope.
To learn more about the Stellaris Elite System, please go to www.bauschsurgical.com. Connect with a representative today if you would like to hear more about how to demo the system in your OR.
Dr. Barry Seibel is the author of the textbook Phacodynamics, published in 4 editions and 5 languages, and he has invented more than 20 surgical instruments for cataract and LASIK surgery. Dr. Seibel is on the clinical faculty at UCLA Geffen School of Medicine and practices in the Los Angeles area.
Financial disclosure: consultant to Bausch + Lomb