Eyeworld

EW FEATURE 94 Current and future IOL choices • March 2018 AT A GLANCE • IOL powers need to be expanded to include those more than 40 D. IOL powers in smaller diopter increments would also be helpful. • Injectors that can go through smaller incisions and preloaded delivery systems for multifocal IOLs would be welcome advances. • The next lenses on the horizon are extended range of focus lenses and trifocals. by Michelle Stephenson EyeWorld Contributing Writer Since their inception, IOLs have undergone many advances, yet there is still room for improvement I OLs come in a variety of mate- rials, and all have advantages and disadvantages. "Weighing all factors, the best material we have right now, in my view, is the Johnson & Johnson Vision [Santa Ana, California] hydrophobic acrylic material," said Doug Koch, MD, Houston. "It has excellent clarity, it is glistening-free, and it has a high Abbe number, which intrinsi- cally reduces chromatic aberration. That said, each material has advan- tages that need to be considered in selecting any IOL design." Additionally, Alcon (Fort Worth, Texas) has a lens with a new materi- al called Clareon, which is available in Europe and will be introduced soon in the U.S. "It appears to be ex- quisitely clear compared to the J&J Vision hydrophobic acrylic material, but it has a higher refractive index and a lower Abbe number," Dr. Koch said. "There's also the Bausch + Lomb [Bridgewater, New Jersey] hy- drophobic acrylic material that is in the enVista, and that is glistening- free but has a higher refractive index and a lower Abbe number." An advantage of the higher re- fractive index materials is that they allow for the creation of a thinner optic. "In the case of the Alcon lens, the material allows surgeons to provide the patient with a full 6-mm refractive optic, independent of the IOL power," Dr. Koch said. "In contrast, J&J Vision reduces the size of the effective refractive zone of the optic as the powers go up in order to maintain minimal variation in IOL central thickness. Also, the tacky surface of the Alcon material appears to reduce the incidence of postoperative rotation of toric IOLs." Hydrophilic acrylic materials are still widely used in Europe, and some of the new IOLs, such as two of the trifocals in Europe, are made of this material. "Unfortunately, because of their risk of calcification, I don't think they will be long-term players in the U.S., unless we can solve this problem," Dr. Koch said. "On the other hand, many interna- tional colleagues love hydrophilic acrylic IOLs for their low reflectivity and hence reduced incidence of positive dysphotopsia." Dr. Koch added that silicone remains a good material, but it has gotten a bad rap. "There are still some excellent silicone IOLs available. Surgeons just have to be cautious about not using them in patients who might potentially need vitrectomy with air fluid exchange or silicone oil injection, or in pa- tients with asteroid hyalosis because that condition could result in calcifi- cation of the posterior surface of the silicone IOL if a posterior capsuloto- my is performed. The bottom line is we don't have the best material yet. Manufacturers are working hard to create them." Jonathan Rubenstein, MD, Chicago, agreed. "There is always hope for improvements in biomate- rials. The goals are something that is as optically pure as possible and has the longest lifespan possible, so it doesn't show any signs of degra- dation," he said. "What we've got now is excellent, and I think it's performing well, but invariably, I think there will be some improve- ments in those biomaterials, again with the overall hope of producing something with optical purity and optical permanence." Range of powers Surgeons agree that the range of IOL powers needs to be expanded. They especially would like to see IOL powers more than 40 D. "The only IOLs available in the single-piece de- sign that are more than 34 that I'm aware of are the Alcon single-piece lenses, and I give them great credit for extending those lenses up to 40," Dr. Koch said. "We need the opportunity to go above that. Patients with nanophthalmos and microphthalmos will occasionally benefit from having higher power IOLs, and we would love to avoid using a piggyback IOL in those patients. It would be nice to have a greater selection of IOLs in negative powers. It would also be nice, in certain instances, to have higher powered toric lenses. It would be nice to have an option to help those patients who have more than 4 D of astigmatism. We can get these lenses on a compassionate use, but it's a complex and expensive process. It's too bad that the FDA won't let us extend those ranges out of the obvi- ous need for selected patients. There will never be a clinical trial to get them approved because of the small number of patients." Kevin M. Miller, MD, Los Angeles, agreed that higher power IOLs are needed. "It would be nice to have these lenses available on a way-in-advance, special-order basis. The lenses could be sitting on a shelf at the manufacturer and be shipped quickly when we need them," Dr. Miller said. "Alternative- ly, they could be manufactured to order. I would love to see lenses go up to 65 D or 70 D on the plus side. In the other direction, the lowest negative power foldable lens is –5 D. I would love to see a –10 D or –15 D. In fact, I'd like to see them go to –20 D in a single-piece design with an appropriately large diameter optic and large haptics," he said. It would also be helpful to have IOL powers in smaller diop- ter increments. "The next hope is that if companies can produce a lens implant with a material that is optically very precise, maybe we can go from 0.5 D steps to 0.25 D steps," Dr. Rubenstein said. "As there's been more hope for refractive neutrali- ty, producing postoperative results with minimal to any refractive error, there's been some hope that going to a smaller refractive step might make a difference. There may or may not be value in that. Clinically, when I see a patient who has 0.25 D residual refractive error or is 0.25 D off the intended refractive error, that usually is clinically insignif- icant. I think this is a goal worth pursuing, but I'm not sure whether it has true strong clinical value or not." Dr. Koch added, "In toric IOLs, we are getting close to the point where we could benefit from some- thing that's less than 1 D. I think the time may be coming for a 0.75 D or a 0.6 D toric because we're doing a better job measuring and understanding both anterior and posterior corneal astigmatism. Also, I agree with Dr. Rubenstein that our IOL calculation accuracy is becom- ing so good that we could improve outcomes if we had IOLs in 0.25 D steps." Current state of IOLs " There is always hope for improvements in biomaterials. The goals are something that is as optically pure as possible and has the longest lifespan possible, so it doesn't show any signs of degradation. " —Jonathan Rubenstein, MD continued on page 96

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