JAN 2014

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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50 EW International January 2014 International outlook Back to the future: Ultrasound gets replaced by laser, again by Matt Young EyeWorld Contributing Writer I n this article we learn about a nanosecond laser that is being developed for use in cataract surgery. Many patients mistakenly believe they are receiving "laser" eye surgery regardless of how it is performed. Ultrasound, laser, femtosecond, bladeless, no stitch—it can all get a little confusing. What patients seem to completely understand is that their friends told them they had a quick recovery and they no longer need glasses. That's the surgery they want. It is safe to assume that most patients will not have a preference about the wavelength or pulse duration of the laser their surgeon uses. Will a new laser—of any wavelength—improve clinical outcomes? Results are the durable metric by which we should assess any new technology. John A. Vukich, MD, international editor T here's no doubt that cataract surgery is evolving from an ultrasound-based surgery to a laser-based one, but that doesn't mean that the femtosecond laser is the clear winner here. A nano laser has emerged in peer-reviewed literature and at the 2013 ESCRS meeting in Amsterdam to add another laser option to the cataract armamentarium. Called the Cetus (A.R.C. Laser GmbH, Nurnberg, Germany), the nanosecond laser by definition operates at a different pulse length than the femtosecond (operating with fewer pulses per minute for a very unique purpose), according to the company's scientific head, Rudolf Walker, PhD. "The femtosecond does tissue separation," Dr. Walker said. "We do tissue destruction. We don't only want to separate [tissue] like the femtosecond does. So whereas the femtosecond would perform cuts for incisions, the rhexis, and separation of the nucleus, we emulsify." Sound familiar? It is, in fact. Unlike the femtosecond, the nano is operated by a handpiece similar to a phaco handpiece, making it manually maneuverable. It differs a little bit in technique, according to Dr. Walker, but you still use a coaxial tip and your manipulator. The advantages of nano appear to be subtle ones, but Dr. Walker suggested they are indeed there. Let's start with the most obvious and perhaps least scientific rationale first. As lasers came to dominate the LASIK arena—from the initial flap to the ablation—many clinics boasted having an "all-laser LASIK" procedure available, a major turn-on for patients who appreciated bladeless surgery. With lasers making inroads into the cataract arena, an all-laser procedure is likewise proving attractive. But a femtosecond laser-assisted procedure is coming with a hefty price tag for surgeons. Dr. Walker asserts that nano is much more affordable. "Our laser is a small box and is quite affordable compared to the femtosecond," Dr. Walker said. The nanosecond must be used in combination with other tools to get the job done in some cases. You can still use a femtosecond rather than a blade to make incisions and the capsulorhexis, for instance. And in some cases, ultrasound may be better for the hardest of cataracts. "Grade 1 to 3+ cataract is ideal [for nano]," Dr. Walker said. "Grade 4 is possible but efficiency drops the harder the nucleus gets. It takes longer. " Dr. Walker noted that A.R.C. only delivers lasers; hence, surgeons still need an irrigation and aspiration system, which he said always comes with a phacoemulsification device. That means every surgeon should have phacoemulsification as a backup for the hardest nuclei. But with either a blade or the femtosecond laser doing the cutting and ultrasound still needed in some cases, one might wonder what the real benefits are of nano. For one, Dr. Walker contends that the nanosecond uses somewhere between 1/5 to 1/10 of the energy that ultrasound uses in cataract operations. "The tip of the laser handpiece does not heat up," Dr. Walker said, and thermal burns have been a traditional concern among phaco surgeons. "No corneal burn is possible with the laser procedure." Femtosecond procedures attacking nuclei—by the fact that they inherently cut rather than emulsify —result in ultrasound needing to take over at some point, Dr. Walker said. "The femtosecond does not replace ultrasound," he said. Nano does replace ultrasound, except that it becomes less efficient with the hardest of nuclei, he said, and a surgeon could opt for phacoemulsification instead. Another interesting though perhaps less noticeable fact about nano at first glance is that the handpiece is disposable. "The procedure is 100% safe in terms of infection risk," Dr. Walker said. "Traditionally surgeons have looked for disposable sleeves, manipulators, etc., but it hasn't been possible to opt for a disposable handpiece. Ours is completely disposable." The tip is also round and polished—more gentle and safe than ultrasound. Meanwhile, here's what the science is saying: At the 2013 ESCRS meeting, Gangolf Sauder, MD, clinical director, Charlottenklinik for Ophthalmology, Stuttgart, Germany, reported 20 patients with mild to moderate cortical cataract underwent cataract surgery utilizing nano. Average duration of surgery from microscope down to microscope up was 9.5 minutes—making it longer than standard phaco—but severe ultrasound shock waves were not present. Endothelial cell count decreased by 4% after three months. "Both coaxial and bimanual chop techniques can be described as successful for up to moderate cortical cataract formation," Dr. Sauder reported. Meanwhile, a scientific article in Clinical Ophthalmology published in September 2013 found that energy was reduced by using nano. A. John Kanellopoulos, MD, clinical professor of ophthalmology, New York University, New York, and director of Laser Vision, GR Institute, Athens, Greece, has had experience with the predecessor technology to the nano over the last 15 years and has published several feasibility studies in the past on laser cataract surgery.1,2 He recently combined the use of femtosecond laser-assisted corneal incisions, capsulotomy and lens fragmentation with the LenSx laser (Alcon, Fort Worth, Texas), and emulsification of the lens fragments with the nanosecond laser, bypassing the need for phacoemulsification utilizing traditional ultrasound phaco technology. In a recent publication he compared femto plus phaco to femto plus nano laser in the study of the contralateral eyes of a 57-year-old female patient who underwent LenSx and phaco in one eye and LenSx and nano in the other. Total energy used was found to be 6 J by phacoemulsification and only 2.4 J by nano. Both eyes achieved 20/20 vision at six months. Copious viscoelastic material, however, was required during the nano procedure in order to prechop the cataract fragments and complete their separation started with the femto laser.3 These differences in energy required may contribute to significant endothelial cell preservation and reduction in postoperative inflammation, both significant parameters in cataract surgery. EW References 1. Kanellopoulos AJ; Photolysis Investigative Group. Laser cataract surgery: A prospective clinical evaluation of 1000 consecutive laser cataract procedures using the Dodick photolysis Nd:YAG system. Ophthalmology. 2001 Apr;108(4):649-54; discussion 654-5. 2. Kanellopoulos AJ, Dodick JM, Brauweiler P, Alzner E. Dodick photolysis for cataract surgery: early experience with the Q-switched neodymium: YAG laser in 100 consecutive patients. Ophthalmology. 1999 Nov;106(11): 2197-202. 3. Kanellopoulos AJ. All-laser bladeless cataract surgery, combining femtosecond and nanosecond lasers: a novel surgical technique. Clin Ophthalmol. 2013;7:1791-5. Editors' note: Dr. Walker has financial interests with A.R.C. Laser. Drs. Sauder and Kanellopoulos have no financial interests related to this article. Contact information Kanellopoulos: ajk@brilliantvision.com Sauder: gangolf.sauder@charlottenklinik.de Walker: dr.walker@arclaser.de

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