Sonic Wave provides lower-energy alternative to phaco

Reduced energy level increases safety, but no changes in technique are needed, surgeon says.

KOLOA, Hawaii — A new non-ultrasound technology assists the surgeon in performing safer and more efficient phacodisruption, according to a presentation here.

Stephen Bylsma, MD, said the Sonic Wave System (STAAR Surgical), uses less energy, causing no turbulence, cavitation or thermal energy. He spoke at Hawaii 2001, the Royal Hawaiian Eye Meeting, sponsored by Ocular Surgery News in conjunction with the New England Eye Center.

“I think that this Sonic system is really where the tool matches the job,” he said. “We don’t have to change our technique.”

Dr. Bylsma said one of the things that makes the Sonic Wave distinct from other phaco machines is that it does not use ultrasonic energy (described as any frequency over 20,000 Hz). While most phaco machines use ultrasound at around 40,000 Hz, the Sonic Wave uses energy between 40 Hz and 400 Hz.

Soft and hard nuclei

With this different form of energy, the Sonic Wave system is more efficient for doing clear lens extraction, a procedure that requires very low energy, said Dr. Bylsma, a private practice physician an assistant clinical professor of ophthalmology at the UCLA-Jules Stein Eye Institute.

“I didn’t think it was possible to chop a clear lens,” he said. “Anytime with ultrasound I had tried to chop a clear lens, I couldn’t get occlusion. In fact, the Sonic acts like a drill and it really promotes occlusion well. So I think it’s the ideal system for clear lens extraction.”

Since ultrasonic energy emulsifies material around the tip, surgeons who use chopping techniques often find occlusion difficult during clear lens extraction. According to Dr. Bylsma, sonic energy helps achieve full occlusion because the tip drills into the nucleus without emulsifying surrounding material.

“It tends to promote the occlusion because it’s acting like a drill,” he said.

The system is also capable of removing very dense nuclei, Dr. Bylsma said. Since there is no risk of a corneal or scleral burn at this lower level of energy, brunescent 4+ cataracts are safer to remove.

“For very strong, 4+ brunescent cataracts, it is helpful to use some ultrasound energy for the grooving portion, but with the Sonic system, that is available with a flick of a foot pedal, and you can remove the quadrants quite effectively,” he said. The Sonic Wave has both sonic and ultrasound components.

Dr. Bylsma said that although ultrasound is faster, the use of lower energy is safer when it comes to cataract extraction.

“The efficiency is good. Ultrasound can remove a cataract faster. The question is, is that extra 20 seconds or 30 seconds of time worth the decreased safety when you compare ultrasound to Sonic?”

Coiled tubing

The Sonic Wave’s fluidics technology also makes the system unique. It uses a coiled tubing system that stabilizes the anterior chamber and helps prevent post-occlusion surge.

“Before the coiled tubing some of the anterior chambers dimpled and collapsed. With the coiled tubing we eliminated the anterior chamber collapse,” Dr. Bylsma said.

According to Dr. Bylsma, the coiled tubing uses a change in direction of fluid within the tube to create a barrier to occlusion rush. The tubing acts like standard tubing at low flow levels, but above 50 cc/min the coils create turbulent flow in the tubing. This way there is no occlusion rush, surge or anterior chamber dimpling.

“The fluidics are really enhanced by the coiled tubing,” Dr. Bylsma said. “Safety is one of the things that we’re after with this system. In perspective, most of the units today are truly powerful and great, but they do require this complex circuitry to avoid the anterior chamber shallowing. One of the things about the coiled tube, it’s a purely passive system and as such, it’s very trouble-free and it’s not just surge reduction, it’s actually surge elimination.”

Since anterior stability can be achieved at vacuum settings as high as 600 mm/Hg with the Sonic, the coiled tubing does not require complicated sensors or circuitry, he said. Also, the machine has the ability to use larger phaco tips because there is no need to prevent occlusion rush. The larger tip allows the surgeon to remove nucleus more rapidly at all fluidic levels.

“They use the coiled tube because then you can really have the high vac, because it’s vacuum that’s removing the nucleus as much as energy,” Dr. Bylsma said. “When you sculpt with the Sonic, you have to go a little slower because it tends to push the nucleus away. You’re not emulsifying at the tip, and with the brunescent 4+ use some ultrasound for sculpting, but once you have freed quadrants then you can switch down to the Sonic system.”

For Your Information:

• Stephen Bylsma, MD, can be reached at 1414 E. Main St., Santa Maria, CA 93454; (805) 925-2637; fax: (805) 347-0033. Dr. Bylsma has a financial interest in this product. He is a paid consultant for STAAR Surgical.

• STAAR Surgical, manufacturer of the Sonic Wave System, can be reached at 1911 Walker Ave., Monrovia, CA 91016; (818) 303-7902; fax: (818) 358-9187.