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EW FEATURE 37 tion to compensate for the positive corneal spherical aberration has been the single most significant improvement in IOL optical per- formance in the past 20 years." How to treat? Intervention may be rare, as some patients can experience improve- ment in their symptoms with time, due to neuroadaptation. However, some patients will never neuroadapt and cannot tolerate the aberrations. "The first thing you need to do is eliminate the refractive error with spectacles or contact lenses," Dr. Trattler said. If the patient has a multifocal lens, ensure there is no significant regular or irregular astig- matism, he added. "Ideally, you want to get the pa- tient back to emmetropia by elimi- nating the residual refractive error," he said, and also recommends evalu- ating the eye to determine if there are any corneal abnormalities such as epithelial basement membrane disease or microstriae in eyes with previous LASIK. If it is a diffractive multifocal IOL, surgeons must ensure that the IOL is not tilted and is centered to slightly nasal in the pupil, "as it must not be decentered temporally," Dr. Holladay said. "Patients who need intervention have to be handled on a case-by-case basis and their complaint is usually of 'waxy vision,'" he said. With both positive and negative dysphotopsia, Nd:YAG removal of the nasal capsule overlying the IOL may be helpful, and secondary pig- gyback silicone IOLs with rounded edges in most cases will eliminate the symptoms. As peripheral capsu- lar opacification may eliminate the problem, it is prudent to wait a few months to be sure the problem does not disappear by itself, Dr. Holladay said. Dr. Kieval will not intervene early on if it is related to the IOL, but rather wait for a few months and try to postpone treatment. "If we can rule out causes other than the IOL design, I explain that most of the aberrations resolve with time," he said. For patients who cannot adapt after 3 to 6 months postop, Dr. Kieval will perform an IOL exchange. "We work with the patients throughout that time frame to en- sure they're comfortable with the decision to wait and see," he said. "This can be especially crucial in multifocal patients." For multifocal patients, that means a lens exchange to either a monofocal or accommo- dating, in order to eliminate the multifocal rings altogether. "Choosing a lens with a round optic edge or a silicone lens is a good option when exchanging the IOL in these patients," he said. What surgeons need to remem- ber about the phenomenon is that likely about 20% of people with a square-edge optic IOL will experi- ence some kind of positive dyspho- topsia, but of those 20%, only around 10% will say it's noticeable or bothersome, Dr. Kieval said. EW References Holladay JT, Lang A, Portney V. Analysis of edge glare phenomena in intraocular lens edge designs. J Cataract Refract Surg 1999; 25:748–52. Holladay JT, Zhao H, Reisin CR. Negative dysphotopsia: The enigmatic penumbra. J Cataract Refract Surg. 2012 Jul; 38(7): 1251–65. Editors' note: Dr. Holladay has finan- cial interests with Alcon (Fort Worth, Texas). Dr. Kieval has financial inter- ests with Abbott Medical Optics (Santa Ana, Calif.) and Lenstec (St. Petersburg, Fla.). Dr. Trattler has financial interests with Abbott Medical Optics and Bausch + Lomb (Rochester, N.Y.). Contact information Holladay: docholladay@docholladay.com Kieval: jkieval@lexeye.com Trattler: wtrattler@gmail.com April 2014 CATz, our latest innovation in Laser Vision Correction, enables surgeons to treat myopic astigmatism with corneal irregularities. CONTACT NIDEK TO ELIMINATE YOUR USER FEES TODAY! 130%6$54t4&37*$&4t5&$)/0-0(*&4 EyeWorld factoid Every year in the U.S., more than one million cataract surgeries are performed. Cataract surgeries are performed with- out complications in 95% of cases. Source: Prevent Blindness America

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