EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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54 54 EW REFRACTIVE April 2012 Soothsaying for multifocal IOLs by Maxine Lipner Senior EyeWorld Contributing Editor measured, all may have a role to play, but we just don't know that at the moment," he said. Polishing the crystal ball From a clinical perspective, refrac- tion appears most telling but has its limitations. "We found that certain parameters like refraction may be helpful but not as helpful or predic- tive as we would like it to be," Dr. Davey said. "This was only about 60- 70% predictive." While post-op vi- sual acuity was very predictive at about 80%, this doesn't do practi- tioners as much good, Dr. Davey pointed out. "We want to predict things before the outcome rather than after the fact," he said. "At the moment we do not have good indi- cators that can help us." There may also be a personality Foretelling which patients will likely need an enhancement W hen it comes to LASIK enhancements after multifocal IOL im- plantation, a patient attaining at least driv- ing acuity is a good indication of whether or not he/she will require a touchup, according to Pinakin Gunvant Davey, O.D., Ph.D., associate professor, College of Optometry, Western University of Health Sciences, Pomona, Calif. Determining who will need an enhancement in such multifocal cases is something that he finds has stymied many ophthalmologists. "The crux of the problem is that as clinicians, we're in a bind—we know that some individuals have problems after multifocal implanta- tion and they're unsatisfied, and there are some individuals who actu- ally become better if you do a LASIK enhancement," Dr. Davey said. "That has become a common occur- rence, and yet we have no idea who those individuals will be or what fac- tors can predict that beforehand." With this in mind, investigators set out to determine which individuals component at play to consider. "Most individuals who have poor acuity happen to be related to refrac- tion, so you can fix it," Dr. Davey said. "But there is a smaller group of patients that has good acuity yet still is unhappy with vision, and that re- quires further investigation." Dr. Davey sees the need for Source: Dimitri Vervitsiotis/Photographer's Choice RF/Getty Images receiving multifocal IOLs were most apt to require a LASIK enhancement. Included in the retrospective study were 104 eyes of patients who underwent cataract surgery from January 2008 to December 2009. Of these patients 20% ultimately re- quired a LASIK enhancement with the multifocal ReSTOR lens (Alcon, Fort Worth, Texas). In the tea leaves In results published in the Septem- ber 2011 issue of Clinical Ophthal- mology, investigators found that determining the important factors was more complex than anticipated. While some factors clearly showed an association, others were much less clear. "A refractive component like pre-operative astigmatism or cylinder was quite predictive," Dr. Davey said. So was post-op acuity. "If they had poor acuity they would be opting for enhancement instanta- neously," he said. "The most excit- ing thing about the acuity is that it turned out to be 20/40 as the cut- off—this just happens to be the driv- ing acuity as well." While no specific question was asked, only routine fol- low-up gathered on how they felt, Dr. Davey thinks that there is likely a connection. "If they can drive then I think they're happy," he said. Some factors, however, appeared confounding. While pre-op astigma- tism garnered from patients' glasses was predictive, looking at corneal astigmatism was not. "This may be for two [reasons]—maybe the glasses refraction is the overall refractive status of the eye, and that gave a global indicator, whereas the corneal astigmatism was only the corneal picture," Dr. Davey said. The other explanation, which he deems purely hypothetical, is that the measure- ments garnered by the Pentacam (Oculus, Lynnwood, Wash.) may not be as accurate as thought. "We are looking at whether some measure- ment errors may have caused our results to not be significant in cer- tain parameters," Dr. Davey said. He acknowledges that there may be other factors at play as well, but because of the retrospective design it was not possible to consider these. "Pupil size, higher-order aberrations, contrast sensitivity, which is not stronger predictive models to better alert patients that they might not be the best candidates for multifocal lenses. "We want to give better prog- nostic outcomes to our patients," he said. "We can forewarn some indi- viduals that for their quality-of-life requirements, multifocals may not be suitable." Going forward, he hopes to find some of these answers. "We require stronger predictive models and more robust pre- and post-op analysis that can come up with a model that in- cludes not only ocular parameters but also quality-of-life and personal- ity parameters that can help us pick these individuals beforehand," Dr. Davey said. He also offered a caveat, noting that the study was done using re- view data involving the ReSTOR lens. "Maybe the data cannot be ex- trapolated to all the lenses," he said. "As always in science, a secondary confirmation will be a nice thing." EW Editors' note: Dr. Davey has no finan- cial interests related to this article. Contact information Davey: 909-469-8473, contact@pinakin-gunvant.com