Eyeworld Daily News

EW SHOW DAILY 26 ASCRS Symposia Monday, April 16, 2018 by Chiles Aedam R. Samaniego EyeWorld Asia-Pacific Senior Staff Writer is simply too subjective. In the fu- ture, refractive surgeons will develop purely objective, highly accurate wavefront refractions. "For the development of IOL power selection methods, the true postoperative refractive state re- mains one of the most problematic aspects," he said. Nevertheless, ophthalmology is experiencing a convergence of tech- nologies for IOL power selection set to raise accuracy from the "accept- able" 80% to the "achievable" 90%, until the elephant in the room, he said, disappears. EW Editors' note: Dr. Holladay has no financial interests related to his presen- tation. Dr. Hill has financial inter- ests with Alcon (Fort Worth, Texas), Carl Zeiss Meditec (Jena, Germany), Haag-Streit (Koniz, Switzerland), and Omega Ophthalmics. companies would be able to transi- tion to exact IOL power labeling on the box. "Current ISO power standards" —as well as the attendant predic- tion error—"will become mostly of historical interest," he said. Other IOL design advances will use the capsulotomy. Optic centra- tion controlled by the capsulotomy will eliminate rotation and reduce negative dysphotopsia. These in- clude the experimental Masket IOL (Morcher, Stuttgart, Germany) in- corporating a capsulorhexis groove and the Bag-in-the-Lens (Morcher) developed by Marie-José Tassignon, MD. Meanwhile, possibly "the coolest thing" Dr. Hill has seen in the last 2 years is the creation of a series of tabs in the capsulotomy as created using the femtosecond laser. These tabs enhance precision during toric IOL placement. Postoperatively, one of the sloppiest things in refractive surgery today is the postop refraction, which aday, who Dr. Hill called the true inspiration for these developments. By decades, Dr. Hill said, things got better and better, the pace in- creasing over the years. He detailed a few things he thinks may incrementally improve IOL power prediction accuracy in the near future. Beginning with preoperative assessment, current methods assign a global measure of refraction over the eye's entire optical system for purposes of IOL power calculation. In the future, an individual index of refraction will be measured for each component part of the visual system. At the moment, the biggest stumbling block for this is the crys- talline lens, the refractive index of which naturally changes over time. Swept-source OCT for the whole cornea is something Dr. Hill also finds exciting. The problem is one of alignment—the devices must be aligned very accurately. Another stumbling block for refractive cataract surgeons are po- tential anatomic differences among ethnic groups. The Chinese and Caucasian eyes in particular, he said, may have anatomic differences that influence IOL power selection. He had noted how his Chinese colleagues tended to have terrible levels of prediction error and how much they hated current IOL calcu- lation formulas for their inaccuracy in their patient populations. Until now, mathematical tools had been inadequate to detect the subtle differences in eyes between ethnic groups; today, artificial intel- ligence is giving us the tools to de- tect and map out these differences. Intraoperatively, one of the most exciting innovations that may soon be available is the Gemini Refractive Capsule (Omega Oph- thalmics, Lexington, Kentucky). The multi-part IOL offers a range of possibilities including simplified IOL exchange, improved ELP estimation, biomonitoring, and drug delivery. Dr. Hill also hinted at "next gen- eration IOL manufacturing that will soon produce hyper-accurate IOLs, with near perfect power accuracy." This will allow precise incre- mental steps, most likely standard- ized to 0.25 D increments, but R ichard Packard, MD, London, U.K., moderator of "Nailing the Best IOL Refractive Outcomes: Let the Experts Update You," lined up "a panel of experts such as you will not find anywhere else on the planet in one room." The symposium was a review of essentials aiming to elucidate how to achieve optimal results when cal- culating IOL power in the full range of eyes, with topics that covered basic optics, the latest formulas, and future advances in technology. The powerhouse panel was fronted by, as Dr. Packard described, "that great guru of IOL calcula- tions," Jack Holladay, MD, Hous- ton, the acknowledged pioneer of IOL power calculations. In his talk, Dr. Holladay said that current data shows that only 50% of surgeons get 75% of their patients within ±0.5 D of predicted refraction; less than 1% get 90% of their patients within ±0.5 D of pre- dicted refraction. This, he said, has to do with the fact that none of the five variables (out of the 16 identified by Sverker Norrby, PhD, in 2008) that account for 99% of prediction error are affected by current IOL calculation formulas. So how can surgeons get their patients up to 95% within ±0.50 D of predicted refraction? In this regard, Dr. Holladay said the future is here: The answer, he said, is in postoperative adjustment. In November 2017, the FDA approved the Light Adjustable Lens (RxSight, Aliso Viejo, California). The IOL, he said, will allow surgeons to get virtually all their patients up to within ±0.50 D of predicted refraction, eliminating prediction error—after the fact. IOL power selection has always been the elephant in the room for refractive cataract surgeons, accord- ing to Warren Hill, MD, Mesa, Ari- zona. Even with modern IOL power calculation formulas, he said, sur- geons essentially just "put the lens in the eye and hope for the best." Nevertheless, Dr. Hill is optimis- tic. The history of refractive cataract surgery has always been one of in- cremental improvements, beginning with the innovations of Dr. Holl- Nailing IOL power calculation Dr. Hill describes incremental improvements to IOL power calculations in the near future.

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