EyeWorld India June 2015 Issue

June 2015 16 EWAP FEATURE The triplet optic involves two convex lenses sandwiching a concave lens and is designed to respond to a small amount of compression. Source: Mark Packer, MD Joining the accommodative movement by Maxine Lipner EyeWorld Senior Contributing Writer AT A GLANCE • Making a lens that mimics accommodative movement continues to be extremely challenging. • Innovative approaches from fluid-filled lenses to a microbattery-powered electrical system are being considered. • Sulcus-based accommodative IOLs have also shown some success. Eyeing new IOLs for improving near vision T he availability of a full- spectrum accommodative lens is among the greatest aims in all of anterior segment surgery, according to Louis D. “Skip” Nichamin, MD, Beaver Creek, Colo. Dr. Nichamin has often referred to this as the “Holy Grail” in anterior segment ophthalmology. “I believe it’s even more so today than ever given the increased awareness and demand for refractive surgery and increased lifestyle treatments,” he said. Mark Packer, MD , clinical associate professor, Oregon Health & Science University, and medical director of Boulder Eyes, Boulder, Colo., agreed, saying that a full- spectrum lens would be a huge winner. “If that existed, we would not have to bother with multifocals and extended depth of focus and pinhole implants,” he said. “That would be the end if we had a reliable, effective, accommodative lens.” Current course In the U.S., there are the options of the FDA-approved Crystalens (Bausch + Lomb, Bridgewater, NJ) and TRULIGN toric intraocular lens (Bausch + Lomb) for those with astigmatism. But Dr. Packer finds that these patients are often not completely spectacle-free and need a low-powered pair of reading glasses. “If you have 20/20 distance vision [with the Crystalens], the average near is going to be 20/40,” he said, adding that the range tends to be from 20/20 to 20/80. Meanwhile, the TRULIGN lens garnered FDA approval but without the “accommodative” label, Dr. Packer said. “The TRULIGN provides increased distance, intermediate, and near vision with reduced spectacle dependence or increased spectacle independence,” he said. Functionally the TRULIGN provides about 1 D of accommodation, but this cannot be measured objectively, Dr. Packer said. Outside of the U.S., while the Crystalens has made some inroads, it is not as popular as it is in the U.S., said Robert J. Weinstock, MD , director of cataract and refractive surgery, The Eye Institute of West Florida. Likewise, the CE- marked Tetraflex accommodative lens (Lenstec, St. Petersburg, Fla.) is being used in some cases but is not a widespread solution, he said. “My understanding in talking to colleagues is that there is not an accommodative IOL in the U.S. or outside the U.S. that is just booming,” Dr. Weinstock said, adding that beyond the U.S. borders, multifocal technology is more favored than accommodative. “I think that’s because there are many more multifocal IOL technologies available and approved outside of the U.S.,” he said. “It’s much easier to make a lens with multifocality than it is to design one that actually moves.” Especially with the FDA climate today in the U.S., it is much more challenging to develop a lens that mimics natural accommodation, he noted. “Stuart Cummings [MD] basically poured his life’s work into developing the Crystalens,” Dr. Weinstock said. “We owe him a debt of gratitude for failing many times and going through about 12 different lens designs before he finally found one that was stable and functional enough to work and to provide the results to finally allow it to get approved—but it’s still not perfect.” In the wings There are currently other lenses in the wings that are beginning to draw attention. Dr. Nichamin pointed to a couple of lenses that go into the ciliary sulcus—the AkkoLens (AkkoLens International, Breda, the Netherlands) and the NuLens (NuLens Ltd., Herzliya Pituach, Israel). The AkkoLens design is two lenses that move perpendicular to the optical axis, Dr. Nichamin said. “In other words, they slide over each other as the ciliary body contracts and relaxes,” he said. “The AkkoLens relies on accommodative forces to move two overriding cubic optical elements in opposite directions.” Dr. Packer thinks this lens works in an interesting way. “It goes in the ciliary sulcus and when the muscle constricts, it compresses the lens and the lens has a variable curvature—as it gets compressed, it increases the accommodative power,” Dr. Packer said. While the number of patients implanted with the AkkoLens is small, it shows promise “with variable amounts of accommodation to reportedly as high as 6 D,” Dr. Nichamin said. The NuLens is also sulcus- based, but works in a contrary manner, he said. Normally in the human eye, as the ciliary body contracts, it causes accommodation; however, with the NuLens it is just the opposite, and despite the counterintuitive mechanism, this approach has worked in some cases. “It seems to work in animals as well as in limited human studies,” Dr. Nichamin said. Some other lenses being developed are more traditionally slated for the capsular bag. Dr. Packer views the Sapphire AutoFocal IOL (ELENZA, Roanoke, Va.), in development, as a fascinating idea. He describes it as a glass photoelectrical device, based on the idea that as someone focuses at near, the pupil gets smaller. “The lens senses this change