EyeWorld India March 2014 Issue

26 EWAP CAtArACt/IOL March 2014 by Matt Young EyeWorld Contributing Writer Back to the future: Ultrasound gets replaced by laser, again This time it’s the nanosecond instead of the femtosecond for cataract surgery 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 nanosecond 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 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 Cetus 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 Cetus 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 Cetus is much more affordable. “Our laser is a small box and is quite cheap 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 Cetus],” 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 Cetus. 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. “That is not possible with the laser procedure,” Dr. Walker said. “No corneal burn is possible.” 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. Cetus 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 Cetus 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 , Department of Ophthalmology, University of Heidelberg, Mannheim, Germany, reported 20 patients with mild to moderate cortical cataract underwent cataract surgery utilizing Cetus. Average duration of surgery 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 technique 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 Cetus.