Novel phaco tip allows carouseling in the bag, enhances hydrodissection, prevents choking

The D-shaped tip with a 20° bend enables the surgeon to enter the peripheral capsule and operate planar to the lens, co-inventor says.

A specially designed D-shaped phacoemulsification tip enables surgeons to perform a new carouseling technique that is faster and safer than other methods, a speaker said.

Balamurali K. Ambati, MD, PhD, MBA, discussed the novel tip and technique at Hawaiian Eye 2011 in Kaanapali, Hawaii.

The tip features a 20° bend to the right, a semicircular bevel and a third irrigation port behind the bevel, Dr. Ambati said.

“The bend to the right enables the tip to be planar with the lens within the capsular bag, while the third port behind the bevel maintains peripheral inflation of the capsule,” he said.

The tip has a reversed flare configuration that lets the surgeon prevent equatorial groove formation and choking at the neck, he said.

“Flow is actually enhanced through the distal shaft,” Dr. Ambati said. “Then there’s no choking at the neck because it actually expands. So, conceptually what’s going on here is that the bend enables planarity within the lens while the peripheral current keeps the peripheral capsule inflated. … Furthermore, the peripheral current induces a laminar counterflow that causes shear on the lens surface comparable to the wall stress in a 60-year-old carotid artery.”

In addition, the third port enhances stability and flow within the bag, Dr. Ambati said.

“In a traditional two-port phaco technique, the fluid vectors within the lens capsule are disorganized. The addition of the third port produces a stream that maintains capsular inflation while streamlining fluid vectors within the bag,” he said.

Dr. Ambati and colleagues from the University of Utah developed the tip in conjunction with MicroSurgical Technology.

Peripheral, planar entry

The surgeon should enter the capsule peripherally, parallel to the floor and planar to the lens, Dr. Ambati said.

The new technique involves a 2.2-mm to 2.4-mm incision; Dr. Ambati said he preferred a 2.2-mm wound.

“It’s important to go as peripheral as possible,” he said. “This may seem counterintuitive, but you want to avoid an epinuclear bowl. By removing the peripheral epinucleus first, the case will go much more smoothly. You can, of course, remove an epinuclear bowl with lower phaco settings but it takes a little bit longer.”

Viscoelastic may help facilitate entry in early cases but is not necessary, Dr. Ambati said.

“The key point is to flatten one’s hand once the lens nucleus is engaged,” he said. “That will keep the tip planar with the bag.”

Dr. Ambati encouraged his colleagues to keep the sleeve as high as possible on the phaco tip to optimize fluid dyanamics.

“Good hydrodissection is key,” he said. “You want to make sure that the lens will rotate. … What I’ve learned recently is that by keeping the sleeve high up on the tip, minimizing the exposed metal, the third irrigation current is more forward and provides better dynamics within the eye and keeps the capsule more inflated.”

Short learning curve

Dr. Ambati said he performed his first eight procedures with the technique on patients with cataracts of grade 3 or lower density. Mean patient age was 64.3 years.

Early outcomes were encouraging in terms of corneal thickness and endothelial cell loss.

“As you would expect, [there was] a slight increase on postop day 1 in corneal thickness, returning to baseline, and a minimal loss of endothelial cell count,” Dr. Ambati said. “Percentage-wise, we’re speaking about a 1% increase in pachymetry at 3 months and sub-5% endothelial cell loss. This is all within the lines of what’s been reported in the literature with other techniques.”

The tip can be used to chop harder lens nuclei, Dr. Ambati said.

“Just go bevel-down, engage and chop as you would normally,” he said. – by Michelle Pagnani and Matt Hasson

• Balamurali K. Ambati,MD, PhD, MBA, can be reached at 65 Mario Capecchi Dr., 5th floor, Salt Lake City, UT 84132; 801-581-3023; fax: 801-581-3357; e-mail: bala.ambati@utah.edu.
• Disclosure: Dr. Ambati reports a financial relationship with MicroSurgical Technology, is a co-founder of iVeena, and is a consultant for Ambrx, Genentech and Inspire Pharmaceuticals.