NOV 2013

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

Issue link: https://digital.eyeworld.org/i/220233

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November 2013 EW International 55 International outlook Emulsify that … IOL? by Matt Young EyeWorld Contributing Writer One surgeon takes phaco to a new level for IOL explantation I t's fun to reflect back on some of the novel—some might say crazy—ideas that have become standard for cataract surgery technique. No-stitch wound closure, piggyback IOLs, topical anesthesia, to name a few, were all the result of unconventional thinking that challenged us to try something new. Now we are presented with another "crazy" idea. Why not use phacoemulsification to remove an implanted IOL when an exchange is indicated? The idea certainly is novel. It may work only with a specific soft, high water content IOL. Some phaco machines may be better suited than others for the task. The point is that many of the innovations in ophthalmology were the result of a wild idea. So is pseudophakic phacoemulsification a "crazy enough" idea to have merit? You be the judge. John A. Vukich, MD, international editor F or years, phacoemulsification has been a standard way to emulsify cataracts before insertion of an IOL, but little if any discussion has addressed emulsifying the IOL itself if something goes wrong— until now. The WIOL-CF (Medicem Technology, Czech Republic) is a novel polyfocal, hydrogel IOL that, according to the manufacturer, more closely resembles lens material than other IOLs, making it resistant to protein, cell deposits, and calcification. While Medicem promotes its use for patients with an active lifestyle to provide near to distance focus without the need for spectacles, Jiri Pasta, MD, associate professor, Charles University, Prague, Czech Republic, has discovered something even more unique—the lens can be emulsified if necessary. "This new approach is possible thanks to unique material with a high content of water, similar to the natural crystalline lens," Dr. Pasta said. Quick facts about the WIOL-CF In addition to the ability to be phacoemulsified, the WIOL-CF has some other interesting, unique features: • Small incision implantation in a partially dehydrated state is possible. • The negatively charged hydrogel stays clear (due to resistance to protein absorption, biofilm formation, calcification, and PCO). • The IOL is elastic and foldable. • The refractive index is the same as the refractive index of the natural human lens. • The size of the optical area is almost twice as large as other IOLs, which the manufacturer says enables optimal peripheral vision and vision under low-light conditions. • Polyfocal hyperbolic optics enable the refractive power to be maximal in the center and gradually decrease to the periphery. • The manufacturer says the lens is both polyfocal and accommodative via shape change. • One investigator found that 85% of patients reached spectacle independence after lens implantation. • While the lens is novel, a much earlier generation of the IOL was developed in 1985 that was biconvex, had a central thickness of 4 mm, and was not foldable. Otto Wichterle, renowned for his invention of soft contact lenses, developed the first generation lens. Source: Medicem Technology Dr. Pasta's discovery began with a challenge. In case of explantation, the lens—with a diameter range of 8.6 to 8.9 mm—has to be explanted into the anterior chamber as a first step, he said. "The manipulation in the anterior chamber is difficult," Dr. Pasta said. "It is impossible to cut the lens with scissors, but with very gentle manipulation, it is possible to cut the WIOL lens by the lens loop. I tried to find a different solution for how to precut, cut, or destroy this lens inside the anterior chamber." In order to explant the lens in a standard way, after cutting by lens loop, the standard incision length is needed, 2.6 to 3.0 mm minimally, Dr. Pasta said. "First, the lens has to be cut into bands for explantation," he said. With the understanding that the lens material has 42% water content, Dr. Pasta examined several phacoemulsification machines that could "sculpt" the WIOL lens in vitro and later in vivo in cadaverous pig eyes. "Emulsifying the whole volume —or even precutting it with phaco— would be very helpful," Dr. Pasta said. "In the case of precutting, it would then be possible to have enough room in the anterior chamber for manual final cutting of the lens for explantation." For this experimental emulsifying, Dr. Pasta cooperated with Medicem to achieve desired results. Therefore, his methods—while unique—are a practical attempt to solve an explantation issue specifically involving the WIOL-CF and other highly hydrated hydrogel lenses. He noted that emulsifying other harder IOLs would not be possible. Still, in an age where some manufacturers are turning more toward hydrophobic lenses due to historic problems with hydrophilic ones, it's worth stopping to consider that highly hydrated IOLs could have some ingenious benefits yet to be realized—such as the ability to explant them via phaco, or maybe via femtosecond laser if Dr. Pasta explores that direction. None of this is easy. Dr. Pasta noted that most phaco machines he analyzed to emulsify the WIOL-CF did not work. Only the Stellaris PC Watch this video on your smartphone or tablet using your QR code reader. (Scanner is available for free at your app store.) (Bausch + Lomb, Rochester, N.Y.) platform did. The Millennium (Bausch + Lomb) and Infiniti (Alcon, Fort Worth, Texas) also were tested, but failed to do the job. "From the mentioned machines, Stellaris is the most powerful in suction, at 550 mm Hg with a small tip diameter," Dr. Pasta said. "It also has a very fast aspiration rise time and a fortified jackhammer effect of shock waves." This shock wave effect could be improved, though, to destroy the IOL further, he said. Nonetheless, Dr. Pasta believes more research needs to be done in this area, calling his research results only "partly positive." "I could be able to sculpt tracks and partly divide the WIOL," he said. "We also didn't find thermal burns of porcine corneas during the experiment." But, he said, the volume of the porcine anterior chamber is incomparably higher than a human one. Dr. Pasta's thinking is clearly the out-of-the-box type that addresses the important issue of explantation. Most discussion of IOLs and innovation centers around getting the lens into the bag, not getting it out. Explantation is still a fear among many cataract surgeons as a worstcase scenario. In the future, with a way to emulsify and extract IOLs with small incisions, it may not have to be. EW Editors' note: Dr. Pasta was involved in the design development and testing of the WIOL-CF lens, but he has no financial interests in the lens. Contact information Pasta: jiri.pasta@uvn.cz

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