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Brad Black, MD offset the slight reduction in con- trast sensitivity. However, these same tradeoffs mean that the multi- focal IOL performance is very unfor- giving of any additional optical or functional compromise. Poor image quality may result from residual re- fractive error, poor centration, and otherwise minor concomitant ocular abnormalities, such as a subtle epiretinal membrane or an irregular ocular surface. Preoperative testing Appropriate attention has been given to assessing the macular pre- operatively, and spectral domain OCT allows us to evaluate its ultra- structural anatomy. However, al- though the slit lamp exam confirms corneal clarity, cataract surgeons have historically tended to overlook the optical quality of the cornea, which may be impaired by an un- even or abnormal ocular surface. Topography provides a qualitative assessment of the corneal surface and may reveal irregular steepening or an abnormal contour. Many topographers now offer additional software analysis that cal- culates the wavefront of the anterior corneal surface. Wavefront analysis adds quantitative data about more subtle higher order aberrations (HOAs) that increase the risk of poor image quality with a multifocal IOL. I use the iTrace (Tracey Technologies, Houston), which can compute corneal HOAs from only the area of the cornea overlapping the patient's scotopic pupil diameter. I particu- larly worry about RMS values of 0.2 microns or more of corneal coma or spherical aberration and will usually recommend against placing multifo- cal IOLs in these eyes. The astigmatism factor There is no question that the optical performance of multifocal IOLs is much less tolerant of residual refrac- tive error compared to monofocal IOLs. Adaptive optics wavefront studies from Scott MacRae, MD, and colleagues at the University of Rochester show that this is particu- larly true for astigmatism. 1 Astigmatic keratotomy is an important adjunct technique for eyes undergoing multifocal IOL im- plantation. Preoperatively, it is im- portant to discuss the possible need for postoperative excimer laser en- hancement of residual astigmatism and spherical error. Intraoperative aberrometry Intraoperative wavefront aberrome- try offers the potential to improve the refractive outcome for any eye. For multifocal IOL patients, intraop- erative pseudophakic measurements may help surgeons to minimize residual refractive cylinder. These intraoperative wavefront aberrometry devices attach directly to the operating microscope and have the advantage of assessing not just the cornea, but the entire ocular refractive state. Pseudophakic meas- urements allow surgeons to make intraoperative adjustments, such as toric IOL alignment. Three potential shortcomings of relying on preoper- ative keratometry or topography are addressed by an intraoperative meas- urement. First, the wavefront refrac- tion will include the contribution of any posterior corneal astigmatism. Second, any astigmatic change induced by the surgical incision should be accounted for. Finally, the surgeon will not be misled if the patient's head was tilted during pre- operative keratometry or topography measurements by the technician. The refractive cylinder axis will be apparent without the need for exter- nal reference landmarks. The value proposition With multifocal IOLs we walk a fine line in an effort to maximize func- tional convenience while minimiz- ing optical compromise. The IOL technology alone doesn't assure good results because this delicate balance can be upset by residual refractive error, subtle macular, corneal, or ocular surface abnormali- ties, and insufficient neuroadapta- tion to unwanted images. Overly optimistic patient expectations are potentially problematic because of our inability to fully control all of these factors. Nevertheless, premium refractive IOLs are the patient value added proposition that restores proper value to our skills as cataract surgeons and clinicians. Many patients want to have refractive options and expect us to help them decide what might best meet their needs. References 1. Zheleznyak L, Kim MJ, MacRae S, Yoon G. Impact of corneal aberrations on through- focus image quality of presbyopia-correcting intraocular lenses using an adaptive optics bench system. J Cataract Refract Surg. 2012; 38: 1724-1733. Dr. Chang is clinical professor of ophthalmol- ogy, University of California, San Francisco, and in private practice, Los Altos, Calif. He can be contacted at 650-948-9123. EW San Francisco 2013 3 Achieving continued from page 2 Attention to detail by Brad Black, MD Advanced IOL platform provides benefits for surgeons and patients " As opposed to looking for things that might 'qualify' a patient for a multifocal IOL, we suggest the surgeon look at every patient as a potential candidate for a multifocal lens, and then determine if there any contraindications to the lens. " Minimizing compromise with the ReSTOR IOL +3 add B oth perioperative and intraoperative approaches to optimizing outcomes with multifocal IOLs have evolved significantly over the past few years, largely due to our increased knowledge of how to en- sure maximum patient satisfaction. While we know patient selection is a major influence, other factors such as capsulotomy size and shape, IOL positioning and orientation, and aggressive treatment of ocular sur- face disorders as well as even small amounts of residual refractive error are equally important. Advances in technology, such as the +3 multifo- cal IOLs (including the AcrySof* ReSTOR* IOL +3, Alcon, Fort Worth, Texas), offer the advantage of excel- lent near vision with minimal com- promise of intermediate acuity. Realistic expectations When a patient expresses an interest in spectacle freedom for near and distance tasks, we consider him or her a potential candidate for multi- focal lenses. In addition to a thor- ough eye exam and patient history, we look at the patient's lifestyle, expectations, and personality. Is this person adaptable? Is he or she motivated to be without glasses? We attempt to establish realistic expectations for the patient. In my continued on page 4 Alcon Monday_SF2103 8pages-DL_Layout 1 4/21/13 7:54 PM Page 3

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