The current decade has been an exciting period for the evolution of phacoemulsification and the development of phaco technology. Computer-controlled power modulation has dramatically reduced the amount of total ultrasound energy needed to remove a nucleus. Micropulse technology, first introduced with the WhiteStar software (Advanced Medical Optics, Inc., Santa Ana, California), has since been incorporated into other phacoemulsification systems. Improvements in fluidics now also allow the use of higher vacuum levels during surgery, further reducing the phaco energy required for cataract removal.
Most recently, latest-generation phaco machines have incorporated lateral phaco tip movements for enhanced cutting power and followability. The first was the Ozil torsional phaco handpiece (Alcon Laboratories, Inc., Fort Worth, Texas), in which the phaco needle rotates and sweeps in a side-to-side motion, like a pendulum.
Advanced Medical Optics recently introduced the Ellips transversal ultrasound handpiece for the WhiteStar Signature system. It also incorporates a lateral motion that, when blended with longitudinal forward-and-back motion, results in an elliptical cutting path (Figure 1). Both phaco modalities emulsify lens material more efficiently by cutting in more than one direction of movement.
Transversal ultrasound can be performed with either a straight or bent tip, depending on the surgeon's preference and comfort. Torsional phaco, on the other hand, requires a bent tip, which may change some surgeons' angle of approach and can make it more challenging to maintain suction. This article describes some of the methods I use to reduce energy use and increase safety with these latest phaco technology advances.
WHY GO LOWER?
Given the reduction in energy introduced with micropulse technology, one could ask why companies continue to invest effort into further reducing phaco energy. The answer is safety. I think transversal ultrasound brings at least three improvements in safety, the most important of which is the potential to better preserve endothelial cell density. Conventional longitudinal phaco, despite many advances, still causes a significant amount of turbulence and trauma in the eye. While this may occur less now than in years past and may even be invisible to the surgeon's eye, it nevertheless causes collateral damage in the form of endothelial cell loss. By minimizing the ultrasound energy and turbulence in the eye, we can also potentially minimize collateral damage to the endothelium. A corollary is that with less endothelial trauma, patients can experience clearer corneas on postoperative day 1, improving the early visual outcome and providing the wow factor that premium IOL patients seek.
A second safety feature of reducing phaco energy is that it may lead to better wound characteristics postoperatively. Excess heat, although it no longer causes frank burns, may still be responsible for subclinical wound burns that lead to postoperative wound gape and leakage.
Finally, better control of the intraocular environment should lead to fewer long-term complications. This is particularly true in harder, grade 3 to 4+ nuclei that present the greatest potential for zonular damage, posterior capsular rupture, corneal edema, and other complications. Because the Ellips will allow the use of lower phaco energy levels more efficiently, we should see a reduction in complications.
For soft nuclei, I think the principal advantage of transversal ultrasound is better followability. Repulsion of nuclear particles is reduced with this technology.
The Ellips handpiece is easy to use, with little to no learning curve other than figuring out how to maximize its benefits. It incorporates longitudinal and transversal modes simultaneously, so the surgeon does not have to switch back and forth as he would with torsional phaco. The proportion of elliptical and longitudinal motion has been optimized for maximum cutting efficiency, requiring no adjustment by the surgeon.
FLUIDICS SAFETY
The fluidics of the WhiteStar Signature also improves intraoperative safety. The Fusion Fluidics system creates such a stable environment that surge is virtually eliminated. With Fusion Fluidics, vacuum levels react immediately to occlusion of the tip, reducing the vacuum to a safer level well before the surgeon could even react (Figure 2).
Fusion Fluidics integrates both Venturi and peristaltic pumps in a single cassette, which is an advantage for on-the-fly adjustments during surgery. I have always liked the linear control for cortical cleanup afforded by Venturi pumps, but I was not willing to give up the safety of the peristaltic pump in nuclear removal. Now, with the dual-pump cassette, I do not have to compromise. I can begin the cataract procedure with peristaltic pump action, then shift to the Venturi pump for better followability of cortical material during irrigation and aspiration. This provides extra safety during the period when the capsular bag is most vulnerable to rupture.
I proactively use a dispersive ophthalmic viscosurgical device (OVD) for increased safety during nucleus removal. As soon as I have removed enough of the nucleus to have access to the posterior capsule, I stop and inject a dispersive OVD behind the nucleus, with the goal of creating an artificial epinucleus. Particularly in dense nuclei, there is no effective epinucleus to protect the posterior capsule against surgical maneuvers and nuclear fragments. A little dispersive OVD behind the nucleus pushes the posterior capsule back and stabilizes the nucleus. My rate of capsular rupture and zonular damage has declined considerably with this approach.
Finally, the WhiteStar Signature is highly customizable for (1) each surgeon's style, (2) lens density, and (3) cataracts of different types. This makes the system more responsive to how the surgeon wants it to behave in all settings.
The safety of WhiteStar Signature with Ellips is important in every case. As more premium IOL procedures are performed, the need to prevent complications proactively, achieve clear corneas the first day after surgery, and ensure a healthy endothelium for many years postoperatively becomes ever more paramount.
Roger F. Steinert, MD, is a Professor of Ophthalmology and Biomedical Engineering; Director of Cornea, Refractive and Cataract Surgery; and Vice Chair of Clinical Ophthalmology at the University of California-Irvine. Dr. Steinert states that he is a consultant to Advanced Medical Optics but has no financial interest in the technology discussed. He may be contacted at +1 949 824 0327; roger@drsteinert.com.
