EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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22 EW CATARACT April 2012 Centering attention on presbyopic IOLs by Maxine Lipner Senior EyeWorld Contributing Editor How to measure the optical center in multifocal lenses C entration is important for any lens, but when it comes to multifocal IOLs, it is more important than ever, according to Eric D. Donnenfeld, M.D., co-chairman, Cornea, Nassau University Medical Center, East Meadow, N.Y. "Modern IOLs have aspheric designs, and if the lens is decentered, the optics of the lens are affected and it induces coma, which causes higher-order aberrations with glare and halo," Dr. Donnenfeld said. "Centering all lenses is important, but for presby- opic lenses it becomes even more important because with their split light, these will be more affected by decentration than a regular lens." The issue becomes where to most effectively put the lens. Dr. Donnenfeld pointed out that some practitioners will try to measure the center of the lens against the dilated pupil, some on the anatomical cen- ter, and some on the visual axis. "The challenge is when the patient's pupil is dilated, it moves signifi- cantly inferiorly and temporally so Source: Dimitri Vervitsiotis/Photodisc/Getty Images that the physiological position of the pupil is more nasal and superior than what you're looking at," Dr. Donnenfeld said. "If you're center- ing your capsulorhexis on the di- Food and Drug Administration (FDA) issues recall for Brilliant Blue G; cases of fungal endophthalmitis reported R ecently, the FDA issued a MedWatch safety alert for four lots of Brilliant Blue G (BBG) ophthalmic solution that were dispensed from a pharmacy in Florida directly to ophthalmologists. The lots have been recalled because of reports of fungal endophthalmitis associated with the use of BBG in vitrectomy. According to the alert, the affected lot numbers are 08232011@80, 10132011@6, 10112011@82, and 10192011@125. Franck's Compounding, located in Ocala, Fla., stated that they notified 22 physicians who received BBG from a batch made in August 2011 and began an immediate recall, and then subsequently recalled supplies from an additional 78 physicians. The pharmacy suggests that healthcare practitioners adhere to pharmacy guidelines, use "single- use" vials as directed, and record patient, procedure, site, product lot, and product expiration date when using this product. Any remaining BBG included in the recall lot numbers should be returned to the pharmacy for credit by calling 352-622-2913. Adverse events related to BBG should be communicated to MedWatch by telephone at 1-800-FDA-1088, by fax at 1-800-FDA-0178, online at www.fda.gov/medwatch, or by mail to 5600 Fishers Lane, Rockville, Maryland 20852-9787. Questions can be directed to Jenny Liljeberg, ASCRS•ASOA associate director of regulatory affairs, at jliljeberg@ascrs.org. lated pupil, you're almost always going to be decentering the lens inferiorly and temporal to where it belongs." Improving lens centration There are several different ways to improve lens centration. One possi- bility includes marking the center of the non-dilated pupil pre-op with a gentian marker. Dr. Donnenfeld prefers to decenter his capsulorhexis nasally from the dilated pupil and make adjustments with the patient's cooperation. "At the conclusion of cataract surgery I ask the patient to look at the center of the three lights on my Lumera microscope (Carl Zeiss Meditec, Dublin, Calif.)—that will tell me the patient's visual axis, which is of most concern," he said. "Then I'll move the lens after the viscoelastic has been removed to center it on the patient's visual axis, and that assures me that the lens is in the right position." He also tends to orient the haptics of the lens su- periorly and inferiorly, which he finds allows him to adjust the IOL more nasally than before. From a technological perspec- tive, Dr. Donnenfeld finds that the TrueVision system (TrueVision 3D Surgical, Santa Barbara, Calif.) can also provide helpful visual guide- lines. "The TrueVision has an over- lay system that allows you to mark the center of the pupil pre-opera- tively and then overlay it on the pa- tient's eye during the surgery so that you can see the undilated pupil when the patient is dilated," Dr. Donnenfeld said. "It shows you where to put the lens in." Another potential wrinkle to take into account in centering a presbyopic lens is the type of anes- thesia used. "If we do a peribulbar anesthesia the patient loses the abil- ity to fixate so we can't establish the visual axis," Dr. Donnenfeld said. "I think in those cases it becomes more important to find the visual axis pre- operatively and mark it." This is one advantage of topical anesthesia he finds. "It gives you real-time evalua- tion of effective lens placement." Dealing with angle kappa Angle kappa must also be taken into consideration and can be particu- larly important in presbyopic IOLs. "The challenge has always been, do you place the lens centered on the pupil, do you place it on the visual axis, or some combination in be- tween?" Dr. Donnenfeld said. "If you center the lens on the pupil and not the visual axis it will induce coma because light entering the eye will not be going to the center of the lens—it will be off-axis." As a result,