EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/78719
70 EW FEATURE February 2011 PRESBYOPIA February 2012 Presbyopia-correcting IOLs on the horizon by Faith A. Hayden EyeWorld Staff Writer Will they ever reach U.S. soil? C ataract surgeons around the world have a common goal: implant patients with a presbyopia-correct- ing IOL that mimics Mother Nature's mechanism of ac- commodation. A handful of devel- opers, including PowerVision (Belmont, Calif.), Oculentis (Berlin), and PhysIOL (Liège, Belgium), be- lieve they've created a lens that comes close to achieving that ideal target. Regretfully, these lenses are not approved in the U.S., although PowerVision and PhysIOL hope their devices reach U.S. soil. "A lot of the product develop- ment has come to a halt with the new climate at the FDA," said Steven Dell, M.D., Austin, Texas. "The translation for that ultimately is products never reach the U.S." Despite the issues with the U.S. market, ophthalmologists and devel- opers worldwide are making strides in solving the accommodation prob- lem. These companies have widely varying approaches, but all are inno- vative, unique, and potentially bene- ficial to the presbyopia patient population. PowerVision's FluidVision FluidVision from PowerVision is a dynamic accommodating IOL in clinical development that changes the shape of the capsular bag by shifting fluid through the structure of the lens (an image is located on page 56 of this issue of EyeWorld). "The mechanism of action takes advantage of extremely small vol- umes of fluid, which are present in the outer haptics, that is forced in the center of the lens as accommo- dation occurs through the natural ciliary body and zonular apparatus," said Louis "Skip" Nichamin, M.D., Laurel Eye Clinic, Brookville, Pa. "Those forces are transferred to the implant, and the fluid is then hy- draulically pushed into the center of the lens." Once in the central optic, the fluid expands, changing the optics' shape by increasing its thickness and therefore its power, explained Samuel Masket, M.D., Advanced Vision Care, Los Angeles. The lens creates myopia while patients are ac- The MPlus IOL Source: Oculentis GmbH commodating so they can see well at near. "To achieve this physically has been no small feat," said Dr. Nichamin. "Theoretically, it blows the mind to think one could do this and then not only do it but show through bench testing, proof of the- ory, and sighted eyes that this con- cept works." The lens has been implanted in man, first in blind eyes in South Africa, then in sighted eyes with re- duced vision. PowerVision demon- strated upward of 5 diopters or more of true accommodation in these pa- tients, Dr. Masket said. Most developmental obstacles have been overcome, although there's always a long, continuing pathway of improvements necessary. One lingering question during the IOL's infancy was if energy could be transferred through the zonular ap- paratus and fibrotic capsule to the pseudophakic lens. "Fortunately, despite consider- able variability from patient to pa- tient in regard to zonular capsule, most have the ability to transfer those vector forces to the still-work- ing ciliary body to this man-made, accommodative, shape-changing lens," said Dr. Nichamin. Three primary hurdles remain: sizing, leakage, and long-term com- plications. Both Drs. Masket and Nichamin were quick to point out that the fluid used in the lens is ophthalmic-grade silicone oil, a sub- stance not foreign to the ocular en- vironment. Although sizing is always an issue when surgeons are putting an IOL into the capsular bag, it hasn't presented a significant problem thus far. "One always wonders what will happen in the long term," said Dr. Nichamin. "Will the lens wear out? We've had accelerated bench testing show the internal movement of the lens should last for many decades, but one doesn't know until it's im- planted in-vivo what type of long- term changes occur as the capsular bag fibroses." FluidVision is about to enter clinical trials in Germany and will hopefully garner a CE mark in the near future. From there, it's on to the U.S. for FDA approval. But de- spite the years-long road ahead be- fore the device reaches U.S. soil, Drs. Masket and Nichamin are confident FluidVision will soon be a func- tional, beneficial IOL. "We're looking for a lens that would match the expectations of both the profession and our pa- tients," said Dr. Masket. "There's no question that the patient base and profession want a true accommodat- ing lens in order to achieve spectacle independence. This is another level of achievement." See "Getting up-close and per- sonal with new accommodative IOLs" on pg. 56 for more informa- tion and an image of the FluidVision lens. MPlus by Oculentis Billed as the "only presbyopia lens with HD-vision," the MPlus by Oculentis has a sector shaped near- vision segment characterized by seamless transitions between near and far vision zones. "There is great visual acuity with the MPlus technology," said Enrico Plessow, marketing manage- ment, Oculentis GmbH. "That's mostly due to the small loss of light. We only have a loss of light of be- tween 5-7%, which is much less than other technologies." The FineVision IOL Source: Erik L. Mertens, M.D., F.E.B.Ophth. "It's a more forgiving lens for surgeons to use, which is why it's popular among them," said Sheraz M. Daya, M.D., Centre for Sight, London. "In terms of the IOL, it's a design where we've got a bifocal that acts like a bifocal in a spectacle frame. There are two focal points on the retina, and the brain tunes things in and out." The problem with the MPlus, said Dr. Daya, is patients don't al- ways see well at near. In his experi- ence, hyperopes are happier with the lens than myopes because my- opes start off seeing well up close anyway. "Hyperopes can't see well at dis- tance or near," he explained. "If they get [a lens] that gives them good distance vision and something more for near, they are very pleased. They don't mind wearing glasses to read fine print. Myopes don't forgive that." The MPlus does cause glare dur- ing night driving in some patients, which they tend to describe as a tri- angle reflecting off a headlight and down onto the road. But Dr. Daya has developed a rather unique way around this problem. "I started putting the lens in up- side down in patients, and that seemed to help with night vision," said Dr. Daya. "They are able to drive because the glare is going up- ward now. They talk about [their vi- sion] having a moon on top, but they are able to cope with that." Dr. Daya implants the lens up- side down in all patients now, and it has not negatively impacted the lens performance. "It's a very good lens for oph- thalmologists who are just starting out in the multifocal world," he said.