Eyeworld

EW FEATURE 41 Neurological keys to bumping up performance of advanced lenses W hen it comes to effi- cacy of premium lenses, dialing in the correct prescription can be only one part of the equation; for some there can be an important neural component to factor in as well. While some pa- tients naturally adapt well to meshing the divergent images of multifocal lenses, for others it can be more of a struggle. EyeWorld took a closer look at potential ways to handle this neural component in conjunction with premium lens use. Unfortunately, in terms of pre- op neural testing to see who might be a good candidate for a premium lens, there really aren't standard ob- jective measurements that exist today, according to George O. Waring IV, M.D., corneal, cataract, and refractive surgeon, Revision Advanced Laser Eye Center, Colum- bus, Ohio, and medical director, division of ophthalmology, St. Joseph's Translational Research Institute, Atlanta. Practitioners must instead rely on objective measure- ments from the eye itself, such as aberrometry, angle kappa, manifest refraction, and health of the ocular surface, in determining good candi- dates. "The clinician develops a gestalt over time as to which pa- tients tend to do better with multi- focal lenses," Dr. Waring said. "Weighing what they do in their daily activities is also very impor- tant." So, for example, someone who drives at night for a living might not be the best candidate. Premium testing In addition to typical testing, practi- tioners now have the ability to tap more sophisticated avenues, such as the use of double-pass wavefront technology, to help understand the role of light scatter. With the device known as OQAS (Optical Quality Analysis System, Visiometrics SL, Terrassa, Spain), Dr. Waring finds that he can offer an objective assess- ment of potential visual quality with premium lenses. "That can give you a sense of the role of light scatter in an eye," he said. But this informa- tion is still in the optical, not the neural, level. However, Dr. Waring sees this as one more factor that can lead practitioners to believe that someone is a good candidate for a premium IOL. Likewise, the role of centration can be particularly important with premium IOLs. Dr. Waring sees the new KAMRA Inlay (AcuFocus, Irvine, Calif.) as making big strides here in helping to identify the estimated line of sight. As part of the AcuTarget System used for implanta- tion, a real-time video overlay is dis- played to show practitioners the proper surgical placement of the inlay. But such a system may also be applicable to premium IOLs as well. "It's just as important for a multifo- cal IOL to be placed in the right po- sition, particularly in a patient with higher degrees of angle kappa, and also to screen out subtle things such as monofixation syndrome," Dr. Waring said. "These are critical com- ponents that lead up to who's going to do well and who's going to neu- roadapt well with these advanced technologies." Since such testing may or may not be covered by insurance, this can present practitioners with a bit of an ethical issue in cataract cases. Should practitioners, for example, do a full evaluation of the tear film and macular health on all patients? And what about topography; is this justified? When it comes to these premium lenses, Dr. Waring thinks so. "You have to know what you're dealing with on every aspect of the eye or else the IOL may not perform like you want it to," he said. "In my mind it's in the best interest of the patient; if you're going to use that advanced technology, you need a front-to-back assessment that gives you a healthy checkmark all the way through and that includes these ad- vanced testing modalities." Visual cortex training Moving beyond diagnostics, one new avenue opening up is the idea of visual cortex training. The idea is to help the brain to neural adapt to the premium lenses by enhancing visual signals. Elkhonon Goldberg, Ph.D., clinical professor, department of neurology, NYU Medical School, thinks that the brain may have a possible role here. "When we talk about the neural substrates of the vi- sual system, we talk about the retina, we talk about certain nuclei in the brainstem and certain nuclei in the thalamus, and finally, we talk about certain cortical areas," Dr. Goldberg said. "My expertise per- tains to this kind of higher cortical level of visual processing, and there is a certain degree of plasticity." When it comes to patients who have experienced strokes or injuries involving the visual system, there February 2011 August 2011 Ethics of IOLs by Maxine Lipner Senior EyeWorld Contributing Editor Premium IOL brain booster: Considering neural testing and plasticity AT A GLANCE • Sophisticated new testing such as light scatter assessment can help to ensure that the eye is optimal and that patients will adapt well to premium lenses • New visual cortex training akin to physical therapy can bump up contrast sensitivity with premium lenses and near and distance acuity • Advanced optics simulators may one day allow practitioners to cherry pick the best premium IOL candidates pre-op continued on page 42

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