Eyeworld

EW CATARACT 32 by Tony Realini, MD, MPH opic errors was reduced by 29% for the Holladay 1 formula, 17% for the SRK/T formula, and 38% for the Haigis formula." Accommodative and monofocal IOLs There is great desire to simultaneous- ly correct distance and near vision with cataract surgery, and there are several ways to accomplish this. One approach is an accommodating IOL. "Accommodating IOLs have been designed to translate ciliary muscle contraction into changes in the focal power of the IOL," said Hon Shing Ong, MD, Moorfields Eye Hospital, London. He and colleagues recently conducted a systematic review to investigate the benefits of accommodative versus monofocal IOLs. Synthesizing data from 4 ran- domized trials, his group reported that while distance corrected near acuity was significantly better at 6 months in the eyes receiving accommodative IOLs compared to monofocal IOLs, at 12 months postoperatively, this benefit was uncertain. There was also some evi- dence to suggest that eyes receiving accommodative IOLs had worse distance corrected visual acuity after 12 months. Dr. Ong acknowledged that there were risks of bias as well as heterogeneity in the included studies. In addition, the data set was relatively small (256 eyes), and all 4 studies utilized the HumanOptics ICU IOL. "Further study is needed to evaluate this issue, and ideally more accommodative and multifocal IOLs will be included." The effect of age Many factors of aging might play a role in cataract outcomes. "Does bi- ometry change due to opacification of the lens?" asked Andreas Hartwig, PhD, University of Manchester, U.K. "Do tear film changes associated with aging have an effect on biome- try? Does keratometry change with age? Are there healing changes with including long eyes, premium IOLs for correction of astigmatism or presbyopia, and potentially even increasing patient age. Several new studies have been reported to address some of this complexity. Long eyes "In eyes with long axial length, current unmodified IOL calculation formulas frequently result in refrac- tive surprise," said Ryan Barrett, MD, Baylor University, Houston. When axial length exceeds 25 mm, he said, "these formulas select IOLs with insufficient refractive power, and hyperopic errors result." Numerous strategies are com- monly employed to address this issue. One is to use a formula designed for long eyes, such as the Olsen or Barrett Universal II formu- las. The alternative is to make an adjustment to axial length before plugging it into a standard formula such as the Holladay 1, SRK/T, or Haigis formulas. A method for axial length optimization in long eyes was recently described by Wang and colleagues, also at Baylor. Dr. Barrett and colleagues com- pared the refractive prediction error (RPE) of the 3 standard formulas above with original and optimized axial lengths in a series of 226 highly myopic eyes, and compared these results to those given by the 2 formulas above designed specifically for long eyes. "Using the standard formulas without optimizing axial length, the mean RPE ranged from +0.20 to +0.49 diopters," said Dr. Barrett. "Using optimized axial length values in the same formulas produced mean RPEs ranging from –0.14 to +0.01 D." This was even better than the formulas designed for long eyes, which had RPEs ranging from +0.16 to +0.23 D, he added. "Axial length optimization decreased the refractive prediction error for all 3 standard formulas and resulted in fewer refractive sur- prises," he said. "Using this simple approach, the frequency of hyper- IOL selection strategies to improve cataract outcomes the most important determinants of outcome occurs before the patient even enters the operating room: selecting the optimal IOL. Many factors complicate this process, A s both surgical technique and IOL technology improve, the expectations for cataract outcomes continue to rise. One of September 2014

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