WhiteStar ideal for bimanual technique, surgeon says

New technology added to the Sovereign phaco platform permits “cold” phaco and appears well suited to a bimanual technique.

Issue: December 15, 2001

AMSTERDAM — WhiteStar technology, a new rapid-pulsed phaco system that permits cataract surgery with reduced heat, may be ideally suited to small-incision surgery and especially to a bimanual technique, according to a presentation here.

One advantage of the rapidly pulsed phaco energy provided by the WhiteStar system, from Allergan Surgical, is its ability to maintain a low temperature during phaco; this provides greater safety, said Richard Packard, MD, FRCS, FRCOphth, who has done a comparative study using WhiteStar.

WhiteStar is a technology upgrade to Allergan’s Sovereign Phacoemulsification System. The system appears to be highly compatible with small incision bimanual techniques, Dr. Packard said here at the European Society of Cataract and Refractive Surgery meeting.

Comparative study

Dr. Packard’s study compared conventional high vacuum phaco using the Allergan Sovereign to phaco using the Sovereign with the WhiteStar technology. He also incorporated the technique of bimanual phaco.

For standard phaco, two incisions were used: a 2.75-mm incision for the phaco tip and a 1-mm incision for the chopper. For bimanual phaco with the WhiteStar technology, two incisions were also used, both of 1 mm. One accommodated the phaco tip and the other the separate irrigation instrument.

Phaco was performed on 50 patients with hard cataracts: 25 with a standard high vacuum technique and 25 with the WhiteStar technology.

Measurements included foot pedal time, effective phaco time, incision size, anterior chamber stability, corneal burns and investigator assessment of ease and efficiency.

Dr. Packard said the WhiteStar technology enabled him to cut and remove hard nuclei with greater ease and less use of ultrasonic energy than conventional phaco. Elapsed phaco time for standard stop-and-chop phaco was 20 sec at 25% power, whereas with the WhiteStar it was 11 sec at 12% power, he said.

This low energy level meant less heat generation, Dr. Packard said. He noted that this was shown by Randall Olson, MD, in cadaver studies also reported here at the same meeting.

Incision sizes were 1 mm, with the irrigation hand piece separated from the phaco tip in the bimanual approach. The irrigation hand piece could be used as a separate instrument to manipulate nuclear fragments toward the tip, Dr. Packard said. The anterior chamber remained stable throughout the bimanual procedures, he said.

“In concert with bimanual phaco, (the WhiteStar technology) permitted safe and efficient cataract removal through small incisions,” Dr. Packard said.

Pulsed ultrasound

“What we’re essentially doing here is pulsing ultrasound energy, rather like a laser. This has the ability to produce the same amount of phacoemulsification as continuous ultrasound but with less burst time overall,” Dr. Packard said.

Improved fluidics with the bimanual technique reduce the likelihood of capsular rupture and can therefore be safer. The “cold” phaco using pulsed power reduces the potential for wound burn.

“Wound burn usually happens with hard cataracts, but it can happen with soft cataracts, such as when the surgeon goes in with phaco on but has not taken out enough viscoelastic. You get occlusion of the phaco tip. With no flow, the tip heats up and you can get a wound burn in 2 or 3 seconds,” Dr. Packard noted.

“If we’re moving toward more clear lensectomies, you want to have the best fluidics available. With WhiteStar you can still have a tight incision without getting a wound burn,” Dr. Packard said.

Burst-rest cycles

The duration of burst and rest modes can be customized to accommodate different parts of nuclear disassembly, with longer burst times for sculpting and shorter times for lens chopping, Dr. Packard said.

“You want to have a range of duty cycles, maybe one that is 700 ms for smooth sculpting, depending on your technique, so you can have a strong hold on the nucleus when using chopping to remove fragments of nucleus,” he said.

Irrigating choppers

Both Dr. Packard and Dr. Olson have designed irrigating choppers that should soon be commercially available. The devices have proven to be efficacious when used with the WhiteStar technology, Dr. Packard said.

With a separate hand piece providing irrigation, the wound size can be made as small as 1 mm to 0.8 mm, Dr. Packard said. This will allow the incision to seal tight to the instrument during surgery. Reduced corneal astigmatism and possibly a reduced postop infection rate may result. The irrigation instrument, inserted through a second incision, can be used as a chopping tool, in addition to its function as a lens manipulator.

Cold phaco

“Because of its ability to pulse much more rapidly, this technology is capable of giving us cold phacoemulsification,” said I. Howard Fine, MD, who presented his impressions of the new technology at the same meeting. “The Sovereign system is a new alteration in power modulations. We can get a short burst of energy. In two pulses per second instead of 250 ms on or 200 ms off, we can dramatically reduce the on portion of that to bursts of energy that are shorter than the threshold for tissue response to thermal injury.”

Dr. Fine said that he and other surgeons have begun using the phaco tip without its sleeve and performing cataract extraction through two side incisions, both of which are 1 mm in size.

For Your Information:
Richard Packard, MD, FRCS, FRCOphth, can be reached at HRH Princess Christians Hospital, 12 Clarence Road, Windsor, England SL45AG; (44) 175-382-92204; fax: (44) 175-38-31-185; e-mail: eyequack@vossnet.co.uk. Dr. Packard has no direct financial interest in any products mentioned in this article. He is a paid consultant for Allergan.
I. Howard Fine, MD, can be reached at Oregon Health Sciences University, 1550 Oak, Suite 5, Eugene, Oregon 97401; (541) 687-2110; fax: (541) 484-3883; e-mail: hfine@finemd.com.

Allergan, makers of the Sovereign system and the WhiteStar software, can be reached at 2525 Dupont Drive, Irvine, CA 92612; (800) 433-8871; fax: (714) 246-5913; Web site: www.allergan.com.