Vacuum and Flow Pump Technologies Incorporated Into the Stellaris

Unveiled during the 2006 American Academy of Ophthalmology meeting in Las Vegas, the Stellaris (Bausch & Lomb, Rochester, New York) represents a unique offering in the market of phaco machines. By obtaining the input of more than 200 doctors and 40 nurses worldwide, not only was the development of the Stellaris thorough and sympathetic to the needs of cataract surgeons, but the machine boasts many user-friendly characteristics for the staff as well.

This system is designed to simplify any method of cataract surgery and functions in either vacuum-based (venturi-like) or peristaltic flow-based modes. The Stellaris offers advanced performance and control features and may be optimized for any phaco technique including microcoaxial or bimanual microincisional cataract surgery. For the surgeon who prefers standard coaxial techniques, the Stellaris technology should improve safety and efficiency with either high- or low-flow and vacuum settings.

When we are considering phaco machines, it is useful to think of them in terms of three major categories: fluidics, power modulation, and ergonomics.

Fluidics. There is no uniform opinion on whether vacuum- or flow-based fluidics is better, but there are certainly advantages to each. In the past, there were either peristaltic or vacuum machines. One of the unique things about the Stellaris is that it offers a choice, so a surgeon may use either flow-based or vacuum-based fluidics, or even a toggle between flow and vacuum characteristics using the new flow module, according to their preference.

The Stellaris phaco machine is capable of vacuum settings of 600 mm Hg and still maintains excellent chamber stability because of its unique ability to simultaneously monitor flow rate and vacuum levels and create feedback through the computer to control pump functions. Furthermore, Bausch & Lomb has optional flow resistance tubing available, which allows high vacuum while maintaining chamber stability even with microincisional surgery. This tubing has a mesh filter that captures lens particles (smaller than 0.3 mm) before they reach the reduced lumen of the evacuation line.

One drawback of past venturi systems was that they required a source of external compressed gas (ie, a tank of gas or a wall outlet). Now, the Stellaris offers enhanced vacuum responses that are generated with an electric pump system internalized in the machine.

Power control. Of course, the three major phaco manufacturers each have their own power control settings, but Bausch & Lomb has raised the bar. The Stellaris now has more options for controlling ultrasonic power using the system's square wave option, or a unique wave form may be created in any of the various pulse or burst modes.

Ergonomics/modularity. The performance of a phaco machine is not defined only by what the surgeon wants and needs. It also involves ease of set up, preventative maintenance, servicing, and overall reliability. Many facilities have a rotating staff, so the easier it is for each person to learn how to set up the machine, the better. There are several ergonomic qualities that set the Stellaris apart. First, the machine's 18-inch high-
resolution screen offers a step-by-step instructional video of surgical set-up to familiarize any new staff member with the process. During surgery, this same screen shows real-time surgery, eliminating the need for a video monitor. Then, there is the blue-tooth wireless foot pedal. This foot pedal is not only extremely responsive and precise, but it relieves the operating theater of too much clutter from exposed wires.

Another ergonomic benefit is the Stellaris' small footprint. It is very maneuverable, but it can lock into place with the touch of a nurse's toe. The instrumentation tray, specially designed in its size and shape, is easily adjusted in any direction with one hand through a sterile drape and has a special drainage feature for when fluid is accidentally spilled.

The titanium handpiece is also very ergonomic. Most phaco handpieces have four crystals. By going to six crystals, the Stellaris handpiece is smaller and lighter. It is also curved for maximum comfort and surgical control. The handpiece also has a unique locking infusion line connector that eliminates the risk of infusion loss and chamber collapse from accidental disconnection of the tubing.

Other benefits of this machine include its online capability for diagnostics and preventative maintenance and its internal modularity, which facilitates upgrades and technical service.

SMALLER INCISIONS
One trend seen over the past few years has been to transition to microincisional cataract surgery. With the available advanced fluidics, power control, and ergonomics, the Stellaris phaco system is not only optimized for standard coaxial but also microcoaxial and bimanual microincisional cataract surgery.

I have been performing phaco since 1978, and I began my transition to microcoaxial surgery through a 1.8-mm incision approximately 2 years ago. If we can go smaller, there may be several advantages, but the question is: Which way do you go smaller?

When bimanual microincisional cataract surgery came along, I gave it a try. Although there were some advantages, I personally did not like having to depend on the sideport incision for infusion. Also, I sometimes find it useful to reposition a patient's head or steady a head tremor, and this was very challenging with bimanual microincisional cataract surgery. Furthermore, the lack of specialized instruments at the time made it difficult to maneuver within the eye. I generally found it less efficient for divide and conquer or supracapsular phaco flip. I, therefore, decided to design a unique needle and sleeve combination specifically optimized for microcoaxial phaco with the Stellaris. I designed this needle with the minimum needle lumen that could still create excellent followability, vacuum-holding force, and aspiration. The needle wall thickness was reduced, but structural integrity was maintained for repeated use. The sleeve was designed with the minimal clearance capable of delivering safe infusion levels at high vacuum.

I first tested the prototype microcoaxial needle and sleeve using a modified Millennium system (Bausch & Lomb). I performed a divide and conquer technique through a 1.8-mm incision and a 0.5-mm sideport incision, 300 mm Hg vacuum, and 117-cm bottle height. The surgery was uneventful, and I perceived no differences between it and my standard 2.85-mm coaxial cases.

I then tested the microcoaxial needle sleeve when I performed the first human cases with the Stellaris system on October 30, 2006. During eight phaco cases, I used standard coaxial in the first four and microcoaxial through a 1.8-mm incision on the remaining cases. I used vacuum levels up to 600 mm Hg at bottle heights of 125 cm with the Stellaris Flow Restrictive Tubing (Bausch & Lomb). This new needle sleeve performed flawlessly, and there were no complications. With this, we concluded that 1.8-mm microcoaxial phaco is now possible with normal fluidics, high vacuum, and relatively normal bottle heights. I have more recently used the microcoaxial Stellaris system for other techniques including phaco chop, divide and conquer, and phaco flip (ie, supracapsular phaco). I believe that microcoaxial phaco is a simple alternative to bimanual microincisional cataract surgery for those who want to move toward smaller incisions.

Terence M. Devine, MD, is Section Chief of Ophthalmology at Guthrie Health, in Sayre, Pennsylvania. Dr. Devine states that he is a paid consultant to Bausch & Lomb. He may be reached at devine_terence@guthrie.org.