A new non-flared Kelman bent tip for torsional ultrasound phacoemulsification retains the same high-cutting efficiency of the mini-flared Kelman tip but without the latter’s propensity for inadvertent prolonged occlusion.
TAKE HOME: A new non-flared Kelman bent tip for torsional ultrasound phacoemulsification retains the same high-cutting efficiency of the mini-flared Kelman tip but without the latter’s propensity for inadvertent prolonged occlusion.
By Cheryl Guttman Krader; Reviewed by Khiun Tjia, MD
San Francisco-A recently introduced phaco tip designed specifically for torsional ultrasound phacoemulsification (0.9 Mini Tip, Alcon Laboratories) provides high-cutting efficiency while minimizing the potential for unwanted prolonged occlusion.
The “mini tip” is a non-flared Kelman bent tip with an 800-µm outer shaft diameter and 570-µm shaft lumen size. Compared with the widely used mini-flared Kelman tip (Alcon), the new mini tip has the same lumen size and a slightly smaller outer diameter.
“The side-to-side, nonrepulsive cutting action of torsional ultrasound makes this technology more efficient than longitudinal ultrasound,” said Khiun Tjia, MD, at the annual meeting of the American Society of Cataract and Refractive Surgery. “However, when torsional ultrasound is performed using a flared tip, there is the possibility of unwanted prolonged occlusion and subsequent temperature increases, especially when operating on denser nuclei.
“In fact, because clogging was happening too frequently with use of the mini-flared Kelman tip, my entire group had switched to a larger tapered tip that had less flare when performing 2.2-mm microcoaxial torsional phacoemulsification,” said Dr. Tjia, consultant ophthalmologist, Isala Clinics, Zwolle, The Netherlands.
The new mini tip also avoids inadvertent prolonged occlusion because of its non-flared design. However, compared with the tapered tip, the mini tip has advantages of being more energy efficient and more suitable for 2.2-mm microcoaxial surgery because of its thinner shaft size, he noted.
Dr. Tjia evaluated the efficiency microcoaxial torsional phacoemulsification using the mini tip and flared tips in groups of eyes matched by age, gender, and nuclear density. All of the procedures were performed by a single surgeon (Dr. Tjia) using the same phacoemulsification platform (Infiniti Vision System, Alcon), surgical technique, machine settings, and viscoelastic.
Analyses of cumulative dissipated energy (CDE) as a measurement of ultrasound efficiency showed statistically significant differences favoring the mini tip compared with the tapered tip in eyes with nucleus grade 1+ cataracts whether comparing mean CDE during the sculpting phase, quadrant removal, or total CDE. The difference between tips was even greater in nucleus grade 2+ eyes.
For the mini tip, mean total CDE values were 7.47 for grade 1+ eyes and 12.17 for grade 2+ eyes. Mean total CDE values for the grade 1+ and 2+ eyes operated on with the tapered tip were 10.77 and 20.17, respectively.
The groups were also compared for fluid use and surgical time, and there were no significant differences between the mini tip and tapered tip for these parameters in either the grade 1+ or grade 2+ eyes.
The greater efficiency of the mini tip is explained by its greater cutting edge displacement compared with the flared tip, he noted.
“At 100% amplitude, maximum excursion for the mini tip is 135 μm but only 90 μm with the thicker tapered tip,” he said.
Dr. Tjia added that with its thinner wall, the mini tip also has a slightly greater cutting edge displacement than the mini-flared Kelman tip. Data from a previous study where he compared CDE for procedures performed with the mini-flared tip and the tapered tip indicate the mini tip and mini-flared tip have similar efficiency.
Because the new mini tip has a slightly smaller port size than the mini-flared Kelman tip, the mini tip may, in theory, have less holding force, he noted.
“However, this has not been a disturbing factor for me in clinical use,” Dr. Tjia concluded.
Khiun Tjia, MD
Dr. Tjia is a consultant to Alcon Laboratories.