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6 by David R. Hardten, MD Multifocal IOLs: Targeting residual refractive error To achieve optimal results, surgeons must plan for patients who require postoperative enhancements T he most common reasons for patient dissatisfaction after implantation of presbyopic intraocular lenses (IOLs) are residual refractive error (sphere and cylinder), glare, and halos. Although patients may lack effective range of focus, most eventually neuroadapt. Cystoid macular edema and dry eye may occur, which must be treated. To improve patient satisfaction with visual results, we need to develop a strategy to effectively manage residual refractive error. Residual refractive error In a multifocal clinical trial, more than 80% of patients who received the Tecnis multifocal ZM900 (Abbott Medical Optics, Abbott Park, Ill.) did not wear glasses. 1 Among those who require glasses after implantation of presby- opic IOLs, residual astigmatism may be one reason. In our cataract practices, more than 70% of patients have 0.5 D of preoperative cylinder or more. 2 To achieve patient satisfaction, resid- ual astigmatism must end up less than 0.5 D. In patients with more than 0.5 D astig- matism, I debulk the astigmatism with astig- matic keratotomy (AK) performed manually or with a femtosecond laser, typically at a 9-mm optical zone. On-axis incisions can be used for small amounts of astigmatism. If there is residual refractive error after implanting a toric or multifocal IOL, we can correct spherical and astigmatic errors with laser vision correction. I tend to perform large corrections earlier. For example, if a patient has 3.0 D astig- matism before surgery, most likely this will remain after surgery. Typically wound edema will disappear and the implant will settle into Figure 1. Laser vision correction used in 59 cases after presbyopic IOL implantation Figure 2. Last follow-up results after laser vision correction following presbyopic IOL implantation 20/20 Dist 20/25 Dist 20/30 Dist 20/25 & J2 20/30 & J3 20/40 & J5 Crystalens 33 eyes; ReZoom 12 eyes; ReSTOR 13 eyes; Tecnis MF 1 eye 100 80 60 40 20 0 place 2–3 weeks after surgery, so I may correct this large refractive error earlier. Most often residual refractive errors range from 0.5–1.0 D. In these cases, I wait 3–6 months, determining whether I first need to perform a YAG capsulotomy. I usually wait 1–2 months to rotate a toric IOL if needed due to residual astigmatism. In 59 eyes in which we implanted various presbyopic IOLs and had residual refractive error, the spherical equivalent was off by approximately 1.0 D, and there was residual astigmatism of nearly 1.25 D (Figures 1 and 2). We used standard LASIK in most cas- es, which is possible if the epithelium and stroma are normal and patients have not had LASIK previously. PRK typically is used if the patient has epithelial basement membrane dystrophy, previous scars, or a longer cataract wound. At that time we used wavefront fairly infrequently, however, as our experience has grown with diffractive IOLs, we are better Methods • Standard LASIK = 44 eyes (75%) • Standard PRK = 3 eyes (5%) • Lift flap custom LASIK = 2 eyes (3%) • Custom PRK = 3 eyes (5%) • Custom LASIK = 7 eyes (12%) • Custom = 20% Standard = 80% Last follow-up results • 59 eyes with at least 3 mo follow-up (mean 12.2 mos) • Mean SE last follow-up = –0.18+0.52 D (absolute of 0.98 D pre-LVC) • Mean astigmatism = 0.41+0.42 D (1.33 D pre-LVC) • No eyes with loss of more than 1 line of BCVA (most 1 line thought to be dryness)

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