Eyeworld

EW FEATURE 104 Current and future IOL choices • March 2018 you far and intermediate, and the weakness is near. The trifocal gives you all three," Dr. Lindstrom said, noting a potential loss of contrast sensitivity and night vision symp- toms with trifocals. "I think [a trifo- cal] is a lens we are going to want to have available, and we will." Small diameter aperture IOLs, such as the IC-8 (AcuFocus, Irvine, California) and XtraFocus (Morch- er, Stuttgart, Germany), allow the patient near vision through the im- planted eye, while the dominant eye functions for distance vision. These types of IOLs, Dr. Lindstrom said, are particularly useful for eyes with significant higher order aberrations because they essentially create a miotic pupil. "It's a lens that has a specific in- dication," Dr. Lindstrom said, men- tioning RK, early PRK and LASIK, keratoconus, and corneal injuries as examples. Dr. Devgan said multifocal de- signs, including EDOF and trifocals, are a "stop-gap measure." "They're just to fill the years ahead of us until we have a truly accommodating IOL. Instead of trying to develop more multifocal lenses, we are trying to develop truly accommodating lenses," he said. Two such lenses are available in the U.S.: the Crystalens (Bausch + Lomb, Bridgewater, New Jersey) and Trulign Toric (Bausch + Lomb). Both have flexible haptics that, with movement of the ciliary muscle, push the optic upward, allowing for an accommodative-like effect. A review published in Current Opinions in Ophthalmology evaluated recent findings on both of these IOLs, finding them to be "constrained by their low and varied amplitude of accommodation. Such limitations may be circumvented in the future by accommodative design strategies that rely more on shape-related changes in the surfaces of IOLs or dynamic changes in refractive index, rather than by forward translation alone." 1 IOLs that do just that are in the works. Dr. Devgan described Juvene (LensGen, Irvine, California), a modular, fluid-optic accommodating IOL currently in trials outside the U.S. The dual-optic design complete- ly fills the capsular bag, preventing capsular bag contraction and pos- terior capsule opacification, while harnessing as much natural ciliary muscle function as possible, he said. Trials with this lens have shown a reasonable degree of accommoda- tion with no glare or halo and intact contrast sensitivity and optical quality. Dr. Lindstrom and Samuel Masket, MD, Advanced Vision Care, Los Angeles, mentioned FluidVision (PowerVision, Belmont, California), still an investigational device in the U.S. This design achieves accommo- dation with fluid changing the IOL's shape based on movement of the ciliary body. Dr. Lindstrom also mentioned two projects that are still in early phases of development or clinical trials: the Sapphire AutoFocal IOL (Elenza, Roanoke, Virginia), which achieves accommodation electroni- cally based on the individual's pupil response, and Lumina (AkkoLens, Breda, the Netherlands), a sulcus im- planted lens that has two refractive plates that slide across each other when moved by the ciliary body. Adjustable While the ability to hit target refrac- tion on the first run is every cataract surgeon's goal, this doesn't always happen. The possibility of an adjust- able IOL is already in sight. The Light Adjustable Lens (Rx- Sight, Aliso Viejo, California), which received FDA approval in November 2017, can be adjusted postop in the office with UV light from the com- pany's Light Delivery Device. "[The IOL] is a special silicone material that you can shift plus, shift minus; you can treat astigma- tism; you can create a bifocal optic; you can even treat spherical aberra- tion," Dr. Lindstrom said. A similar concept uses a femtosecond laser system (Perfect Lens, Irvine, California) to induce a chemical reaction for refractive index shaping of an implanted IOL. Research involving this technolo- gy has shown it to be effective at inducing changes in commercially available hydrophobic and hydro- philic acrylic IOLs with some of the most recently published research in a rabbit model showing its biocom- patibility. 2 "I think both of the adjustable IOLs are somewhat of a disruptive innovation rather than an incre- mental innovation," Dr. Lindstrom said. "If we could take all patients we've done surgery on—they have a little myopia, a little astigmatism, a little hyperopia—and we can offer them that adjustment to exactly what they want—or if they were do- ing monovision and we were just a tiny bit off—that would be extraor- dinary. … It would be like doing a YAG laser capsulotomy, minimally invasive but being able to adjust the power." Tackling current design flaws and beyond While many next generation IOLs seek to address presbyopia and missed refractive targets, some seek to address other current issues asso- ciated with IOLs. More than a decade ago, Dr. Masket set out to create an IOL that prevents a significant visual compli- cation, negative dysphotopsia. "We know that the greatest cause of dissatisfaction after un- complicated cataract surgery is dysphotopsia in some form," Dr. Masket said, noting that while industry made some strides to ad- dress positive dysphotopsia, he was challenged by negative dysphotop- sia intellectually. "We will do what we consider to be an anatomically perfect surgery and the patient may have 20/20 acuity and be very un- happy with the outcome of surgery. "The problem is not statis- tically insignificant," Dr. Masket continued. "The best epidemiologic study came from [Robert] Osher, [MD], and he found that as many as 15% of patients will complain of negative dysphotopsia in the early postoperative period. Owing to neuroadaptation, this reduces over a period of time so that in the end it's only about 3%. But if we're doing 3 million cataract surgeries a year in the United States and we have a 3% incidence of a certain problem, it means we're creating 100,000 un- happy people a year. The magnitude is significant." Dr. Masket started looking at commonalities in negative dyspho- topsia cases. He found that negative dysphotopsia didn't occur with sulcus placed lenses, anterior cham- ber lenses, or those positioned with reverse optic capture; if it occurs, it's with in-the-bag lenses. "But there are downsides to putting the lens in the sulcus and downsides to popping the lens ante- riorly while leaving the loops in the bag. I decided to make a lens that would mimic the concept of having some part of the optic over the ante- rior capsule but would still have the bulk of the lens in the capsular bag, so it would eliminate some of the other side effects. That was the con- cept of the lens," Dr. Masket said. The CE-marked Masket ND IOL Type 90s (Morcher) is designed with a groove to accept the anterior capsulotomy for placement. To date, there have been no cases of negative dysphotopsia in patients with this lens, Dr. Masket said. According to him, the lens is universal. It has haptics if the cap- sulotomy ends up being unsuitable for capsulotomy fixation (incom- plete, wrong size, decentered) or it can accommodate sulcus fixation as well. It can be made in a multifocal or toric fashion. In addition, to the Masket ND IOL, there are two other capsulo- tomy fixated IOLs—Femtis Laser Lens (Oculentis, Berlin, Germany) and bag-in-the-lens (BIL, Morcher). There are "countless advantages" to a capsulotomy fixated IOL, Dr. Mas- ket said, among them being negative dysphotopsia prevention, axial and rotational stability of toric IOLs, lim- ited tilt, avoidance of capsule con- traction, more predictable ELP, and reduced higher order aberrations. Other IOL design improvements that others are working on, which Dr. Masket called "pipe dreams"— he's not convinced they're needed —are ones that would allow for an even smaller incision size and poly- mers that could refill the existing capsular bag. Dr. Lindstrom said he would like to see an IOL that prevents pos- terior capsule opacification among the design or material modifications made in the future. Currently, Dr. Devgan said, there is no perfect lens on the market. "Every lens has some great upsides and some significant down- sides," he said. "We have to balance that and match that to the appropri- ate patients. Patient happiness is the difference between the results that we get and what their expectations were. Certainly, we want to maxi- mize our results, but also we need to be smart; we need to temper our patients' expectations." EW References 1. Pepose JS, et al. Benefits and barriers of accommodating intraocular lenses. Curr Opin Ophthalmol. 2017;28:3–8. 2. Werner L, et al. Biocompatibility of intraoc- ular lens power adjustment using a femtosec- ond laser in a rabbit model. J Cataract Refract Surg. 2017;43:1100–1106. Editors' note: Dr. Devgan has financial interests with LensGen. Dr. Lindstrom has financial interest with Alcon (Fort Worth, Texas), Bausch + Lomb, Johnson & Johnson Vision (Santa Ana, California), and Carl Zeiss Meditec (Jena, Germany). Dr. Masket has financial interests with Morcher and PowerVision. Contact information Devgan: devgan@gmail.com Lindstrom: rllindstrom@mneye.com Masket: avcmasket@aol.com A range continued from page 102

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