American Academy of Ophthalmology Web Site: www.aao.org
Clinical Update: Cataract
Pick Your Favorite Phaco Tools
What are your favorite phacoemulsification tools and how do you make the most of them? Five experts provided advice on the latest devices, settings and approaches for state-of-the-art surgery. Here’s what they had to say.
Mark Packer, MD
The Sonic Wave (Staar) introduced sonic frequency phaco several years ago, enabling cooler tip temperatures and microincision techniques. While slower for extraction of denser nuclei, the Wave achieves outstanding chamber stability despite high vacuum levels with coiled Super Vac tubing and the Cruise Control (Staar), an inline flow restrictor capable of diminishing surge flow to safe levels. While the Cruise Control can be applied to any phaco machine, it does necessitate a change in parameters.
Occlusion-mode phaco was first made available on the Diplomax (AMO) and similar technology is now available on most state-of-the-art machines. This programming allows the pump to sense when vacuum rise signals the development of occlusion. It also permits the surgeon to control speed. Small changes in these settings can mean dramatic differences in surgical efficiency, as material comes more quickly to the tip and a firm hold develops more rapidly, allowing quick and successful chopping and extraction of material.
For bimanual microphaco, I use the 20-gauge Duet System (Micro Surgical Technologies), using the front-end irrigating choppers. I prefer the open-ended irrigator for refractive lens exchange and soft nuclei, the canoe paddle-like vertical chopper designed by Hiroshi Tsuneoka for 2 to 3 + nuclei, and a chopper I designed, nicknamed the Packer penguin, for dense cataracts. I use a 30-degree straight 20-gauge phaco needle. The capsulorhexis forceps designed by Micro Surgical Technologies permit reproducible initiation of the tear with a central pinch and exquisite control throughout completion. A small (4-millimeter-diameter), centered capsulorhexis is essential for optimal function of the Crystalens IOL (Eyeonics), and microincision surgery facilitates chamber stability during capsulorhexis construction by disallowing egress of viscoelastic.
A clear corneal microincision should be tight enough to prevent significant outflow, trapezoidal to allow adequate instrument mobility, and capacious enough to prevent tissue damage and loss of self-sealability. A variety of diamond knives now meet these criteria.
Dr. Packer is clinical assistant professor of ophthalmology at Oregon Health & Science University and is in private practice in Eugene, Ore. He receives travel and research funds from Alcon and AMO.
Douglas D. Koch, MD
My standard approach is stop-and-chop. For sculpting the groove, I use 40 pulses per second with 80 percent “on” time. I begin chopping using 40-ms linear burst, and I remove segments using 50 pulses per second with 40 percent “on” time. I use the Neosonix with a 0 threshold for sculpting and a 20 percent threshold for the second and third phases of nuclear removal. With a high pulse rate, one can reduce chatter through a combination of low energy and high pulse frequency. I recognize that these settings are unique to the Alcon device, but similar principles can be applied to other machines that offer sophisticated power modulations.
Dr. Koch is professor of ophthalmology at Baylor College, Houston. He is a consultant for B&L, Alcon and Pfizer.
Samuel Masket, MD
Irrespective of the emulsification machine, as long as the eye is protected against surge, I prefer to work with the phacoemulsification tip with the bevel facing toward the lens. Typically, that would be bevel down for initiating phaco-chop maneuvers. The key to success with chop methods is to achieve and maintain occlusion of the tip. In this way, the vacuum will build and hold the lens material firmly in order to enable chopping maneuvers, irrespective of whether one is using a vertical or horizontal chopping method.
Dr. Masket is clinical professor of ophthalmology at the University of California, Los Angeles, and is in private practice in Century City, Calif. He is a consultant to AMO and a member of the Alcon speakers’ alliance.
David F. Chang, MD
Phaco surgeons must master an interdependent confluence of instrumentation, technology and technique. We must dynamically adjust our machine parameters according to our technique and to individual characteristics of the eye and the nucleus. I have long thought that combining video teaching with an illustrated textbook would be the best instructional approach for such an objective. I finally collaborated with the faculty from my Academy phaco chop course to produce such an integrated approach.²
Dr. Chang is clinical professor of ophthalmology at the University of California, San Francsico, and is in private practice in Los Altos, Calif. He is a consultant for AMO, a consultant and U.S. medical monitor for Visiogen and has received educational travel support from Alcon, but has no financial interest in any instruments or devices mentioned.
Randall J. Olson, MD
Directly related to the duty cycle (the amount of time ultrasound is on), the decreased energy used results in less wound heating, and I feel this represents a decreased risk of wound burn. The latest 6.0 software of White Star, which starts out at a very long duty cycle and increases only as necessary, has even further diminished my ultrasound time, and further improved followability.
I have transitioned from horizontal to vertical chop, which allows me to use greater mechanical effort without having to go outside the pupil and has improved the speed, efficiency and, I think, safety of my nucleus removal. Horizontal chop, however, is a nice back-up tool in difficult cases.
Fortunately, ultrapulse technology requires no learning curve. One can use any nucleus removal approach. I would start with 5 or 6 ms on and 12 to 20 ms off as a good starting point. The rest of the parameters should be whatever you currently use.
As far as phaco chop goes, take a good course, such as the one that Dr. Chang has at the Academy. Then use the approach as outlined: first, chop quadrants, then chop hemi-nuclei, then move to the full approach. With a little experience, it is easy to see the advantages, particularly in tough cases.
Dr. Olson is chairman of ophthalmology at the University of Utah, Salt Lake City. He is a consultant for AMO and heads the Medical Advisory Board for Calhoun Vision.