EyeWorld Asia-Pacific June 2018 issue

June 2018 EWAP FEATURE 25 to be “constrained by their low and varied amplitude of accom- modation. 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, Califor- nia), a modular, fluid-optic accom- modating IOL currently in trials outside the U.S. The dual-optic design completely fills the capsu- lar bag, preventing capsular bag contraction and posterior capsule opacification, while harnessing as much natural ciliary muscle function as possible, he said. Trials with this lens have shown a rea- sonable degree of accommodation with no glare or halo and intact contrast sensitivity and optical quality. Dr. Lindstrom and Samuel Masket, MD , Advanced Vision Care, Los Angeles, mentioned Flu- idVision (PowerVision, Belmont, California), still an investigational device in the U.S. This design achieves accommodation 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 electron- ically based on the individual’s pupil response, and Lumina (Ak- koLens, Breda, the Netherlands), a sulcus implanted lens that has two refractive plates that slide across each other when moved by the ciliary body. Adjustable While the ability to hit target refraction on the first run is every cataract surgeon’s goal, this doesn’t always happen. The possibility of an adjustable IOL is already in sight. The Light Adjustable Lens (RxSight, Aliso Viejo, California), which received FDA approval in November 2017, can be adjusted postop in the office with UV light from the company’s Light Delivery Device. “[The IOL] is a special silicone material that you can shift plus, shift minus; you can treat astig- matism; you can create a bifocal optic; you can even treat spherical aberration,” 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 tech- nology has shown it to be effective at inducing changes in commer- cially available hydrophobic and hydrophilic acrylic IOLs with some of the most recently published research in a rabbit model showing its biocompatibility. 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 of- fer them that adjustment to exactly what they want—or if they were doing monovision and we were just a tiny bit off—that would be extraordinary. … 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 as- sociated with IOLs. More than a decade ago, Dr. Masket set out to create an IOL that prevents a significant visual com- plication, negative dysphotopsia. “We know that the great- est cause of dissatisfaction after uncomplicated 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 unhappy with the outcome of surgery. “The problem is not statisti- cally 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 unhappy people a year. The magnitude is significant.” Dr. Masket started looking at commonalities in negative dys- photopsia cases. He found that negative dysphotopsia didn’t occur with sulcus placed lenses, anterior chamber lenses, or those posi- tioned 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 anteriorly 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 anterior 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 concept of the lens,” Dr. continued on page 26