MAY 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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48 EW REFRACTIVE SURGERY May 2013 Managing cataract surgery in post-LASIK cases by Erin L. Boyle EyeWorld Senior Staff Writer W ith the amount of patients who have had refractive surgery and now need cataract surgery increasing, an effective approach is needed to achieve the best results in these cases. "We're seeing more and more of these patients now coming in for surgery; LASIK was approved for use in 1995, so it's been almost 20 years that we've been seeing these patients," said Eric D. Donnenfeld, MD, clinical professor of ophthalmology, New York University Medical Center, New York. "Ophthalmologists should be prepared for a large number of these patients coming in for cataract surgery over the next several years. [Ophthalmologists] need to be prepared and willing and able to treat these patients to achieve the visual results that patients are accustomed to with the quality of vision that they had for years following LASIK." Felipe A. Soria, MD, Vissum Corp., Alicante, Spain, and Instituto de la Vision, Montemorelos, Mexico, said surgeons, especially those just entering ophthalmology, are seeing more cases that have undergone previous procedures before cataract surgery. "What the future holds for us young ophthalmologists is very challenging," said Dr. Soria. "Nowadays [there are] so many procedures being done in young adults and adults, [such as] corneal inlays, phakic IOLs, LASIK, PRK, corneal rings, crosslinking, scleral procedures for presbyopia, etc., that we need to be prepared to manage when the patient will need a cataract procedure." "The first waves of the tsunami of previous refractive patients seeking cataract surgery are arriving, but many tsunamis are yet to come," he said. Preoperative care and managing patient expectations are key in these cases, said Richard M. Awdeh, MD, assistant professor of ophthalmology, director of technology transfer and innovation, Bascom Palmer Eye Institute, Miami. Post-refractive patients have experienced excellent visual results and are accustomed to being spectacle-free, he said. "They've had prior LASIK and they can see distance perfectly, so now they're coming in for cataract surgery, and they're saying 'I have a cataract, can you take it out? I want to see how I did before.' That's the conversation where you want to gently set the expectation and help them understand that these are two different types of procedures for two different types of problems," Dr. Awdeh said. Preoperative Overall preoperative measurements can be of great help in achieving the best results, Dr. Soria said. "Knowing the pre-refractive information and the post-refractive information six months after surgery will help to obtain a more reliable understanding of the corneal power and a more accurate IOL power," he said. Dr. Donnenfeld and Dr. Awdeh outlined additional preoperative measurements that are important. Correct lens selection can be difficult in these patients, they said. "The biggest issue with operating on patients who had previous LASIK is achieving a good uncorrected vision following surgery," Dr. Donnenfeld said. "There are many mathematical models that have been created to increase the chance of having a good outcome. Originally we used the historic method, which we have found to be one of the least reliable methods for achieving good outcomes. ASCRS has developed a wonderful … post-LASIK calculator, which allows surgeons who are operating on LASIK patients to input all the available data and to look at different formulas for finding the right IOL power. The modified Masket formula is my personal favorite." Imaging the posterior surface of the cornea can assist in finding posterior curvature, as well as evaluating the corneal thickness map for the residual corneal bed. That result can assist in determining the need for enhancement following cataract surgery as well as the type of lens that should be used, Dr. Awdeh said. "If there is irregularity on the topography or on the Oculus Pentacam [Arlington, Wash.] imaging, then that may drive the selection of the type of lens that we put into the eye," he said. Surgeons also need to determine if previous LASIK patients had myopic or hyperopic LASIK, Dr. Donnenfeld said. "In general, myopic LASIK induced positive spherical aberrations and hyperopic LASIK induced negative spherical aberrations. This can be measured in a variety of different ways in the office, but in general, I like to place a negatively aspheric lens in a patient who has had myopic LASIK and a zero aberration lens in a patient who has had hyperopic LASIK to achieve optimal higher order aberration correction and sharper vision," he said. Additionally, the health of the ocular surface should be assessed and treated if necessary, physicians said. Patient expectations Lens opacity and the LASIK flap Source: Felipe A. Soria, MD Discussing potential results precataract surgery is of vital importance with post-refractive patients, all three physicians said. Dr. Donnenfeld said he alleviates patients' fears that their refractive surgery caused their cataract by telling them, right away, that the previous surgery had nothing to do with their cataract. These patients are often good candidates for presbyopic lenses, he said, but should be counseled about the benefits and limitations. There are several caveats with presbyopic lenses in these cases: "Patients with decentered ablations as seen on topography do not do well," Dr. Donnenfeld said. "Patients who have the old oblate ablation profiles, which you can see on topography as very central flat areas and then a rapid change to a steep area without a transition zone, also do not do well. And patients who have very high myopia or hyperopia don't do well with presbyopic IOLs." Dr. Soria said knowing patient expectations could assist with postoperative satisfaction rates. "An important [issue to be evaluated] is the patient's expectation to become spectacle-free," he said. "IOL power calculation in post-refractive patients is not accurate, and patients must be informed of this. The overall satisfaction of the patient according to his needs is better than achieving emmetropia." Performing surgery Performing cataract surgery on a post-refractive case requires care, Dr. Awdeh said. "When I perform the surgery, I will be very cognizant of the prior flap that is present. I will plan my incisions around those previous flap incisions," Dr. Awdeh said. "I don't want to plan my side port incision or my wound to overlap with the prior LASIK flap because I don't want any risk of lifting the flap or having a tear near the wound or the side port." He said he often moves his incisions more peripheral to avoid the prior LASIK flap. EW Editors' note: Drs. Awdeh and Soria have no financial interests related to this article. Dr. Donnenfeld has financial interests with Abbott Medical Optics (Santa Ana, Calif.), Alcon (Fort Worth, Texas), and Bausch + Lomb (Rochester, N.Y.). Contact information Awdeh: richard.awdeh@gmail.com Donnenfeld: ericdonnenfeld@gmail.com Soria: soriafelipe.md@gmail.com

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