“Having a low energy, high efficiency
modality like OZil makes it a very good fit with micro-coaxial
James A. Davison, M.D.
Learning curves are almost non-existent,
making the transition easy and safe
Torsional phaco with OZil 12 tip reduced quadrant removal time versus longitudinal with a straight tip
Technological advances in phacoemulsification have helped us improve patient outcomes by making the surgery safer while compromising none of our desired visual outcomes.
For years, surgeons have looked for various methods to reduce ultrasonic energy used during phaco. We have learned that ultrasonic energy correlates with corneal endothelial cell density loss, so using less energy would therefore be safer.
Reduced energy was first introduced in the Legacy and INFINITI pulse and burst modes (Alcon, Fort Worth, Texas), and later with the WhiteStar system (Advanced Medical Optics, AMO, Santa Ana, Calif.). Other methods, such as NeoSoniX (Alcon), AquaLase (Alcon), and Nd:YAG laser all had slight improvements as well.
Torsional phaco using the mini-flared tip with the Ultra sleeve, the latest technological advances, combines stable fluidics with a limited irrigation flow while maintaining a secure wound construction and allows IOL insertion through a 2.2-mm incision. Oscillatory torsional amplitude creates a lateral tip movement that shears lens material and has proven more efficient in its cutting, thereby reducing the amount of amplitude and thermal energy needed. In traditional phaco, you first impale and cut into the nucleus, then aspirate the emulsified material. The phaco tip will break the impacted nucleus into fragments, but the other nuclear material itself is not really emulsified.
The INFINITI Vision System with the INTREPID Fluid Management System (FMS) (Alcon) maximizes the safety of these techniques through a design that utilizes more rigid aspiration tubing that reduces post-occlusion surge.
How micro-coaxial phaco differs
The INFINITI with torsional ultrasound uses a more efficient fluidics system in which fluidic turbulence by the vibrating tip is almost completely eliminated. The OZil 12 tip does not “kick” the nucleus material and, therefore, results in less repulsion, increased holding power, and more contact between the nucleus material and the phaco tip.
Compared to traditional phaco, torsional itself cuts very efficiently. There is less heat, less thermal damage to the wound, and it is very quiet. In essence, we are delivering less energy into the eye, which allows surgeons to effectively use smaller and more pristine incisions. That, in turn, means almost no surgically induced astigmatism and faster healing.
The ability to control fragments better is a significant advantage of using the INFINITI system. Com-partmentalizing the quadrants allows surgeons to organize their removal, minimizing fragment endothelial abrasion.
The torsional tip is able to penetrate deeply into the nucleus and keep the nucleus at the tip for emulsification.
Also, because you have much less fluid surrounding the phaco tip there is a small clean reservoir, so the thermal cuts become more significant to micro-coaxial surgery. Having a low energy, high efficiency modality like OZil makes it a very good fit with micro-coaxial surgery.
Wound integrity and construction
Wound integrity continues to be an integral part of advanced phacoemulsification, and micro-coaxial phaco offers the opportunity for better wound integrity. The OZil 12 tip geometry translates to 50% reduction of stroke within the incision compared to traditional phaco, and there is a two-thirds reduction in thermal energy compared to longitudinal ultrasound.
Torsional tip motion uses quadrant aspiration. Advantages to that include a sweeping effect, less fragment repulsion, greater fragment adherence, improved fragment control, improved followability of nuclear material, and improved efficiency ratio of internal work action compared to incisional friction.
As we’ve discussed, a traditional phaco handpiece delivers less than 50% effective longitudinal ultrasound energy. Torsional phaco allows us to use 100% effective energy delivery, with more cutting power.
If we’re going to stay with larger incisions and high infusion sleeves, we can go to a higher flow rate. With torsional, vacuum levels and flow rates can be raised without affecting efficacy.
If we use micro-coaxial incisions, there’s no need to lower the fluidic parameters; they can remain where they would for the incision sizes. In my experience, a 2.2-mm incision made with the ClearCut INTREPID blade (Alcon) feels no different than a 3.2-mm incision with a high infusion sleeve. It’s a seamless transition.
The combination of torsional tip motion, more rigid cassette design, and angled tip design creates the most efficient contemporary phacoemulsification process that enables more surgeons to embrace micro-incisional phacoemulsification.
James A. Davison, M.D., is in private practice at the Wolfe Eye Clinic in Marshalltown, Iowa.