Eyeworld

EW CATARACT 30 May 2014 by Michelle Dalton IOL cutters: What goes on behind development EyeWorld spoke to several physicians whose names adorn IOL scissors to find out how they took concept to reality M ost surgeons do not expect to remove the IOL that they are implanting during cataract surgery, but there are some cases where that must be done. "I'm often asked to name the best IOL, and my response is that it's the one that's easiest to remove when the next best lens comes along," said Richard Mackool, MD, founder of the Mackool Eye Institute, New York. Surgeons must make several intraoperative decisions when ex- planting a lens, Dr. Mackool said, including whether or not to remove or amputate the haptics, how many segments to divide the IOL into, when viscodissection is adequate, and how and in what location to insert the new IOL. "Happily, the surgical need for IOL removal or exchange is uncom- mon," he said. But when the situation does arise, a key component to the surgery is the choice of IOL scissors/ cutters. EyeWorld spoke to several surgeons whose names adorn these instruments—and here are their stories (in alphabetical order). Mackool Foldable Lens Removal System Before the advent of the Mackool Foldable Lens Removal System (Impex Surgical, Brooklyn, N.Y.), relatively large profile instruments and a correspondingly large incision were required to simultaneously fix- ate and explant an IOL, Dr. Mackool explained. "Often there wasn't ade- quate space in the anterior segment for both the implant and the instru- ment." So, about 8 years ago, Dr. Mackool "thought it would make more sense to use two smaller in- struments—one a small forceps in- serted through a sideport incision and used to fixate the IOL, and the other a microscissors that fits easily through any phaco incision of 2 mm or greater that would cut the im- plant in half." Dr. Mackool added "teeth" to the distal end of both the scissors and forceps so that after the IOL was cut, either instrument could easily grasp and remove each segment. "The ease in freeing the haptics is the factor in determining whether to remove or amputate them," Dr. Mackool said. In general, the haptics become as tightly encased within the capsule as they are going to become by 4 to 6 weeks. He and his son, R.J. Mackool, MD, have previously reported that removal of the lens epithelium from the undersurface of the anterior capsule by vacuuming will delay the process for several months. Finally, Dr. Mackool said the biggest difference between silicone and acrylic lenses is that the former are "slippery" with a thinner optic edge but a thicker central optic. "Forceps tend to slide off them eas- ily and forceps with teeth tend to cut through them," he said, adding he often uses a microhook placed on the opposite side of the optic to fixate the IOL as the scissors are used to divide it. Packer/Chang IOL cutters Like most innovations in cataract surgery, the Packer/Chang IOL cutters (MicroSurgical Technology, MST, Redmond, Wash.) were devel- oped because of limitations, said co-designer Mark Packer, MD. "In this case, the initial inspira- tion was microincisional cataract surgery," he said. "I had started performing 1.4 mm biaxial phaco, and there weren't any instruments that could easily fit through that wound size." Dr. Packer approached Larry Laks (from MST), who "was the glue that put it all together. [David Chang, MD] and I were both work- ing on similar ideas, but we had no idea what the other had been doing until Larry brought us together." Dr. Packer worked on the size element of the scissors, while Dr. Chang wanted to ensure the scissors "were able to cut through any- thing." At the time, they were both implanting the ReZoom (Abbott Medical Optics, Santa Ana, Calif.), and the acrylic material "was at the time the hardest foldable material marketed. Most scissors got the lens material caught between the jaws in- stead of cutting the lens." According to Dr. Packer, MST developed a scissor that could cut through that acrylic material without bending the blade. Dr. Packer said that concept to final, marketed instrumentation took close to 3 years, but most of that time was trying to find the right manufacturer. "The whole idea didn't gain traction until Larry came on board, and from there and with David's interest, it took about 6 months." Ironically, the scissors then became part of the Synchrony IOL (Visiogen/Abbott Medical Optics) clinical trial, as the protocol demanded that if the lens was not stable in the bag, it had to be explanted. For any burgeoning instrument developers, Dr. Packer recommends developing a concise mission state- ment and (if remotely talented) "sketch what you envision." Otherwise, it may be difficult for manufacturers and/or colleagues to understand the concept. The Snyder/Osher forceps (left) have channels on the inside of the rectangular jaws that hold the IOL optic firmly during cutting. The scissors (right) have fine serrations that grasp slippery IOL materials during each cut. The scissors have a rounded tip. Source: Michael E. Snyder, MD The blades of the Packer/Chang IOL cutter are shown incising a lens. A new, single-use, disposable version is scheduled for release this year. Source: Mark Packer, MD continued on page 33 Device focus

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