Recent fluidics innovations improve overall phaco safety and efficiency

Leading cataract surgeons discuss the unique advantages of several new systems and the impact on intraoperative fluidics.

Fluidics has always played a crucial role in safe and efficient cataract surgery. Today, recent advancements in technology and surgical technique are changing the way surgeons manage inflow, outflow and vacuum during phacoemulsification.

Three of the latest-generation phaco machines recently approved for use in the United States, the Stellaris Vision Enhancement System (Bausch & Lomb), the WhiteStar Signature System with Fusion Fluidics (Advanced Medical Optics) and the Infiniti Vision System (Alcon), offer unique enhancements to fluidic controls, according to the manufacturers.

Ocular Surgery News spoke with several leading cataract surgeons to present their tips for maximizing the new technologies and for avoiding common pitfalls.

WhiteStar Signature System

The WhiteStar system, which was launched at the American Society of Cataract and Refractive Surgery meeting in San Diego, is the follow-up to the Sovereign system.

David F. Chang

OSN Cataract Surgery Section Members I. Howard Fine, MD, and David F. Chang, MD, were clinical investigators of the machine and shared their experiences with OSN.

They said the system’s main innovation is a feature called Fusion Fluidics, which combines and enhances AMO’s previous innovations in chamber stability and for the first time allows surgeons to switch between a peristaltic pump and a venturi pump intraoperatively.

“The fact that you can use peristaltic for a certain portion of the procedure and venturi for another portion is a great advantage,” Dr. Fine said. “For instance, I like peristaltic for chopping and mobilizing quadrants, and I like venturi for mobilizing the epi-nucleus because it gobbles it so quickly.”

Dr. Chang agreed. “I could have a venturi system programmed for my chop memory setting, a peristaltic system for my fragment memory setting and a venturi system for the epi-nucleus and cortex.” He also said this feature improves the efficiency of using a smaller 20-gauge phaco tip.

“Nothing beats a 20-gauge phaco tip with a peristaltic pump for safety, and this is my routine preference,” he said. “However, this combination can be slow for denser nuclei. Being able to combine hyperpulse and a micro-tip with a venturi pump at selective stages of the case will undoubtedly increase the popularity of 20-gauge phaco tips, with a net gain in safety.”

Another feature is the surge-preventing CASE Technology (Chamber Stabilization Environment), which is incorporated into the Fusion Fluidics software.

“The machines now create a virtual anterior chamber that mirrors what’s going on in the real anterior chamber. So it is sensing changes and is quicker at sending adjustments to the real anterior chamber. It’s getting more responsive,” OSN ASCs Section Member William J. Fishkind, MD, FACS, said, adding that the system reacts “almost instantaneously.”

In practice, CASE is effective in preventing surge, Dr. Fine said.

“You can program a certain up-threshold of vacuum, and after you reach that threshold, which of course depends on occlusion, it will go to a higher vacuum, and it will stay there for a certain period of time before dropping down to a lower vacuum so as to minimize surge,” Dr. Fine said. Surgeons can program their desired up- and down-thresholds, as well as the duration of maximum vacuum, he said.

“They’ve also fused CASE with occlusion-mode phaco, so you can also set a change in power at the time vacuum comes or clears,” Dr. Fine said. “In other words, you can have a different power for an un-occluded tip than for an occlusion. It switches automatically.”

The merging of CASE-controlled vacuum with occlusion-mode phaco has proved beneficial for reducing intraoperative time and power, Dr. Fine said.

“When we used it, we really got a reduction in effective power. We’re doing a much larger portion of the removal of the cataract with Fusion Fluidics, although I’ve used it on only 4 or 5 different days. For grade 2 [or higher] nuclei, I was using about 2 seconds of effective phaco time and 2% power. For grade 3 [or higher] nuclei, it was about 3 seconds and 3% power,” he said.

Infiniti Vision System

The Infiniti Vision System has the advantage of offering torsional phacoemulsification, according to Drs. Fine and Fishkind.

William J. Fishkind

“It’s a new technology and it’s exciting,” Dr. Fishkind said. “It’s extremely efficient at moving the equation to pre-occlusion so that there just isn’t any surge.”

Torsional ultrasound is a power modulation modality available with Alcon’s OZil torsional handpiece. In torsional ultrasound, the phaco tip moves side to side, which shears lens material, as opposed to traditional longitudinal ultrasound in which the tip moves back and forth. Torsional ultrasound reduces repulsion of lens material, can be performed through smaller incisions and is associated with an increased thermal safety profile.

In terms of fluidics, torsional ultrasound offers the key advantage of pre-occlusion phaco, in which the lens fragments do not need to occlude the phaco tip in order to be sheared, emulsified and removed, according to these surgeons.

“Torsional phaco works best when the piece is free and not occluding the tip, and that ultrasonic oscillation of the tip shears nuclear material. Torsional phaco is actually less efficient when it’s occluded,” Dr. Fine said.

“If you could assure that you have 100% pre-occlusion, you’d never have surge,” Dr. Fishkind said. “I think torsional is probably 98% occlusion-free. It’s a big step.”

In another attempt to minimize post-occlusion surge, the Infiniti also offers a phaco tip with the Aspiration Bypass System — a small hole in the side of the tip that allows fluid to flow through even during occlusion.

“It allows fluid to flow through the tip at all times, which blunts occlusion. It’s a clever method of trying to keep occlusion and surge to a minimum,” Dr. Fishkind said.

OSN Cataract Surgery Section Member Uday Devgan, MD, FACS, noted that, while useful for preventing surge, the tip requires surgeons to increase their vacuum to compensate for the flow through the hole.

“The problem is like drinking a milkshake through a straw that has a hole in the side. You get some leakage of fluid there, and you have to use high vacuum. So if I use 300 mm Hg of vacuum in a straw without a hole, with a hole in the side I’m going to have to use 400 mm Hg of vacuum,” he said.

Stellaris phaco system

The Stellaris Vision Enhancement System, also launched during the ASCRS meeting, is the follow-up to the Millennium system.

According to OSN Practice Management Section Member Elizabeth A. Davis, MD, FACS, one of the clinical investigators of the machine, one of its main advantages is its EQ Fluidics Management System, which equalizes fluidic dynamics such as aspiration and flow during procedures for good chamber stability whether using conventional or advanced microsurgical techniques. The Stellaris EQ fluidics also allows a “balance between a vacuum-based and a flow-based system.”

Elizabeth A. Davis

“You can either select and operate solely with one or the other or, if in different segments of your surgery you prefer one vs. the other, then you can toggle back and forth,” she said.

“So in a sculpting or chopping mode you can start out with a peristaltic type of system, and then when you go into segment removal you can switch over to vacuum-based system,” she said.

Unlike the WhiteStar system, which allows on-the-fly shifting between venturi and peristaltic pumps, the Stellaris’ flow module is able to emulate vacuum characteristics without actually having to switch pumps.

“It’s important that new generation phaco machines have fluidic pumps that can give both peristaltic as well as venturi performace in order to increase both efficiency and safety,” Dr. Devgan said.

Another advantage of the Stellaris is Bausch & Lomb’s proprietary restrictive outflow tubing, Dr. Davis said. “It increases the resistance to outflow so as you build vacuum during occlusion and then occlusion breaks, you won’t have this sudden gradient of pressure from inside the eye to outside the eye into the tubing and then the collapse of the anterior chamber,” she said. The tubing also includes a mesh filter to prevent nuclear fragments from clogging the outflow, she said.

Bausch & Lomb has also increased the fluid cassette capacity from 250 cc to 300 cc, Dr. Davis noted.

“This seems like a minor thing, but in surgery it becomes significant. So now in the middle of the case you don’t have to stop surgery and change the cassette because it’s filled with fluid. And the system also monitors it with a display on the screen,” she said.

Overall, the Stellaris is “completely balanced” and enables cataract surgery with minimal or no surge, Dr. Devgan said.

“The Millennium had great fluidics, and the Stellaris has even far surpassed that. And that certainly increases the margin of safety for you,” he said.

Fluidics present challenges in MICS As surgeons perform microincision cataract surgery with smaller and smaller incisions, they will be confronted with unique fluidics-related challenges, Uday Devgan, MD, FACS, said. “The problem is, as you decrease the size of your incisions, you have to decrease the size of the tubing of your instruments. And as the tubing size decreases, you need higher vacuum to achieve even a low level of flow,” Dr. Devgan told Ocular Surgery News. “Two years ago, people were saying, ‘how small can you go?’ Well, you can go as low as you want, but you’ve got to ask yourself how low a level of flow do you want.” Having low flow significantly increases intraoperative time, William J. Fishkind, MD, FACS, told OSN. Without adequate inflow, he said, “there tends to be more surging, and therefore you have to cut down the aspiration flows to maintain deep chambers. With a small tip, that really slows things down.” “It’s like drinking a milkshake,” Dr. Devgan said. “If you are drinking a milkshake and you use a tiny cocktail straw, it will take forever.” He described the relationship between incision size and intraoperative time as an “exponential curve.” According to Dr. Fishkind, flow problems are not the only fluidics complication in bimanual microincision cataract surgery — in order to prevent outflow through the wounds, he said, the incisions have to be tight around the instruments. “That inhibits movement, stretches the wound and creates difficultly in closing the incision postoperatively,” he said. Surgeons have devised a variety of creative methods for increasing flow, Dr. Devgan said, including bottle height extenders, anterior chamber maintainers and forced infusion pumps. However, a less complicated and safer solution is simply to return to the “sweet spot” of 2-mm incisions, he said. “It is all about balance between the small incisions and the fluidics,” he said. “We are coming back to about plus or minus 2 mm. For the micro-coaxials, it is now between 1.8 mm and 2.2 mm.”

Try before you buy

In comparing these three new machines, several surgeons agreed that they all offer excellent fluidic controls and that their choice of one machine over another is tied to personal preference.

Dr. Devgan compared the machines to luxury cars. “One is a BMW, one’s a Porsche, one’s a Mercedes. They’re all great cars,” he said. “They just drive a little bit differently. You decide what’s right for your personality, for your surgical technique. You can’t decide which phaco machine to buy without test-driving it.”

He recommended that surgeons who are used to a particular platform go out and try one of the newer systems.

For more information:

• William J. Fishkind, MD, FACS, can be reached at 5599 N. Oracle Road, Tucson, AZ 85704; 520-293-6740; fax: 520-293-6771. Dr. Fishkind is a paid consultant for AMO.
• Uday Devgan, MD, FACS, can be reached at the Maloney Vision Institute, 19021 Wilshire Blvd. #900, Los Angeles, CA 90024; 310-208-3937; fax: 310-208-0169. Dr. Devgan is a paid consultant for Bausch & Lomb and AMO and has received award monies from Alcon.
• I. Howard Fine, MD, can be reached at 1550 Oak St., Suite 5, Eugene, OR, 97401; 541-687-2110; fax: 541-484-3883. He is a paid consultant for Bausch & Lomb and AMO.
• David F. Chang, MD, can be reached at 762 Altos Oaks Drive, Suite 1, Los Altos, CA 94024; 650-948-9123; fax: 650-948-0563. Dr. Chang is a consultant for AMO, Alcon and Visiogen.
• Elizabeth A. Davis, MD, FACS, can be reached at Minnesota Eye Consultants, 9801 Dupont Ave. South, Bloomington, MN 55431; 952-567-6067; fax: 952-885-9942. Dr. Davis is a paid consultant for AMO, STAAR Surgical, Bausch & Lomb and Ista Pharmaceuticals.

• Advanced Medical Optics, maker of the WhiteStar Signature System, can be reached at 1700 E. St. Andrew Place, Santa Ana, CA 92705; 714-247-8200; fax: 714-247-8672; Web site: www.amo-inc.com.
• Alcon, maker of the Infiniti Vision System, can be reached at 6201 South Freeway, Fort Worth, TX 76134; 817-293-0450; fax: 817-568-6142; Web site: www.alconlabs.com.
• Bausch & Lomb Surgical Inc., maker of the Stellaris Vision Enhancement System, can be reached at 180 Via Verde, San Dimas, CA 91773; 800-338-2020; fax: 800-362-7006; Web site: www.bausch.com.

• Andy Moskowitz is an OSN Staff Writer who covers all aspects of ophthalmology.