EyeWorld Asia-Pacific June 2018 issue

EWAP FEATURE 11 Current state of IOLs by Michelle Stephenson EyeWorld Contributing Writer 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. Since their inception, IOLs have undergone many advances, yet there is still room for improvement I OLs come in a variety of materials, and all have ad- vantages and disadvantages. “Weighing all factors, the best material we have right now, in my view, is the Johnson & John- son 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 num- ber, which intrinsically reduces chromatic aberration. That said, each material has advantages that need to be considered in selecting any IOL design.” Additionally, Alcon (Fort Worth, Texas) has Clareon, a lens with a new material which is avail- able in Europe and will be intro- duced soon in the U.S. “It appears to be exquisitely clear compared to the J&J Vision hydrophobic acrylic material, but it has a higher refrac- tive index and a lower Abbe num- ber,” Dr. Koch said. “There’s also the Bausch + Lomb [Bridgewater, New Jersey] hydrophobic 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 refractive 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 postopera- tive 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 calcifica- tion, 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 international colleagues love hydrophilic acrylic IOLs for their low reflectivity and hence reduced incidence of positive dysphotop- sia.” 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 ex- change or silicone oil injection, or in patients with asteroid hyalosis because that condition could result in calcification of the posterior sur- face of the silicone IOL if a poste- rior capsulotomy 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 degradation,” 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 design 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 nanoph- thalmos 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 compas- sionate 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 obvious need for selected patients. There will never be a clinical trial to get them ap- proved because of the small num- ber 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 continued on page 12 June 2018